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www.lancet.com/psychiatry
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Series
Lancet Psychiatry 2015
This is the first of two papers in a
Series about bullying
Department of Psychology
(Prof D Wolke PhD,
N Tippett PhD, S Dantchev BSc)
and Division of Mental Health
and Wellbeing, Warwick
Medical School, University of
Warwick, Coventry, UK
(Prof D Wolke)
Correspondence to:
Prof Dieter Wolke, Department
of Psychology, University of
Warwick, Coventry, CV4 7AL, UK
D.Wolke@warwick.ac.uk
Bullying 1
Bullying in the family: sibling bullying
Dieter Wolke, Neil Tippett, Slava Dantchev
Sibling relationships have a substantial and lasting eect on children’s development. Many siblings experience some
occasional conflict, however, up to 40% are exposed to sibling bullying every week, a repeated and harmful form of
intrafamilial aggression. We review evidence on the precursors, factors relating to peer bullying, and mental health
consequences of sibling bullying. Parenting quality and behaviour are the intrafamilial factors most strongly
associated with bullying between siblings. Sibling bullying increases the risk of being involved in peer bullying, and
is independently associated with concurrent and early adult emotional problems, including distress, depression, and
self-harm. The eects appear to be cumulative, with those children bullied by both siblings and peers having highly
increased emotional problems compared with those bullied by siblings or peers only, probably because they have no
safe place to escape from bullying. The link between sibling and peer bullying suggests interventions need to start at
home. Health professionals should ask about sibling bullying and interventions are needed for families to prevent
and reduce the health burden associated with sibling bullying.
Introduction
Increasing evidence suggests that sibling bullying, a form
of aggression that is carried out repeatedly, adversely
aects the mental health of children. We review how and
why sibling relationships might aect child development
and mental health, what sibling bullying is and how it
relates to rivalry and aggression between siblings, and its
prevalence and what family factors are associated with it.
Furthermore, the association between sibling and peer
bullying will be reviewed and the eect of sibling bullying
on mental health outcomes explored. Some general
programmes dealing with sibling relationships in families
are identified and future directions of investigation and
clinical interventions are discussed. We argue that sibling
bullying is an important factor to consider in children’s
development generally, and in particular, by health-care
professionals involved with mental health.
Siblings
Most children worldwide have siblings. In the UK, more
than 85% of adolescents have at least one sibling;1 in
other regions, several siblings in a family is the norm,2
with the largest ospring size identified in sub-Saharan
Africa.3 Exceptions exist, such as the One Child Policy in
China between 1979 and 2013 (when it was relaxed),
which restricted the number of children that urban
couples could have to one.4
Sibling relationships are usually the most enduring
relationships during the lifetime.5–7 By middle childhood,
children spend more time interacting with siblings than
with parents.8 Siblings have an important role in each
other’s lives as companions, teachers, and caregivers,9
and can substantially contribute to each other’s develop-
ment and adjustment. Siblings might have either a direct
(ie, related to child–sibling interactions) or indirect eect
(ie, related to one child’s eect on parents and therefore
on siblings) on each other’s development.10 Positive
sibling ties and interactions can help with the acquisition
of skills that are important in cognitive development,11,12
provide emotional support,13 and buer siblings from
adverse life events,14 including marital conflicts15 or poor
peer relationships.16 Furthermore, sibling relationships
are independently associated with later adolescent
adjustment and wellbeing, even after controlling for
parental and peer influences.17–19
Sibling rivalry
Sibling relationships, however, are not always har-
monious and supportive. Severe sibling jealousy and
rivalry have been documented since ancient times, most
notably through the story of Cain and Abel in the Old
Testament. The term sibling rivalry was coined by child
psychiatrist and psychoanalyst David Levy to refer to
jealousy of the mother’s love.20 He used an experimental
projective approach with children aged 2–13 years, in
which clay dolls were used to represent a baby at the
mother’s breast and an older child standing next to them.
Children were asked: “And then the [brother or sister]
sees the new baby at the mother’s breast. [He or she]
never saw him before. What does he do?” The young
children’s responses often involved attacking the baby
doll, ie, destroying, biting, tearing, or crushing it with
their feet.21 This action was often justified as being a
prohibitive parent: “The baby is bad”, “because she was
bad. She wanted to hit the baby”, or “we don’t need two
babies in one house”. Levy’s studies in various
populations and tribal societies led him to conclude that
sibling rivalry is a universal situation in human beings
regardless of their dierent cultural forms, arising
directly from biological behaviour. He concluded that
sibling rivalry, the aggressive response to the new baby, is
so usual that it is a common feature of family life.22
Sibling rivalry stemming from a newborn baby can be
conceptualised within Miller’s23 Frustration–Aggression
hypothesis, which postulates that the occurrence of
aggression always presupposes the existence of
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frustration. People can easily see that a first child might
be frustrated by the arrival of a new child in the family.
Assuming equal care, the 100% attention that the first
child once had will be at least halved, whereas a second
child will only ever have had 50% of attention. For a new
arrival, this attention will be further reduced to 33% and
so on. In the triangle of sibling rivalry, which comprises
the sibling, their beloved parent, and their rival sibling,
this rivalry is shown in the form of initial frustration and
later jealousy, a complex social emotion. Indeed, the
presence of jealousy and related behaviours have been
linked to persisting poor sibling relationship quality.24
Some cultural dierences in the nature and dynamics
of sibling relationships have been shown, most notably
according to individualistic or collectivistic norms. In
collectivistic societies, which place greater focus on
group rather than individual goals, siblings spend more
time together and have more hierarchical relationships,
with older siblings commanding greater respect, but also
taking on the responsibility of providing care for younger
siblings.25,26 Accordingly, cross-cultural comparisons have
shown sibling relationships in collectivistic or family
oriented societies to have greater support, companion-
ship, intimacy, and satisfaction than in individualistic
societies.25,27–29
Sibling aggression or sibling bullying
The absence of an accepted definition and the use of
diering terms such as aggression, violence, abuse,
bullying, or rivalry, has been a barrier to investigation
on sibling aggression.1,7,30 Whenever possible, we focus
on sibling bullying, which is a form of aggression
between siblings that involves direct or indirect
intentional and persistent behaviours with an imbalance
of power (panel 1). Therefore, we exclude infrequent or
singular acts of aggression, which can be better
described as sibling rivalry, and incidents of extreme
violence or sexual abuse, which might be criminal in
their nature.7
In view of the similarities between children’s
relationships with siblings and peers,32,33 bullying seems
to be the most appropriate term to use for several
reasons. The first reason is that bullying occurs in
settings where individuals do not have a say in which
group they want to be in. This is the situation for both
children in school classrooms and those at home with
their siblings. In an analogy to experimental studies on
social defeat in animals, this might be thought to be
similar to siblings being caged together in the same
space,34 often in the absence of an adult, which leads to
familiarity that can breed contempt.35 The second reason
is that siblings dier by sex and age, thus are rarely equal
in terms of size, or physical or mental strength. Older
siblings might use their size advantage to bully a younger
sibling, and boys might have more physical strength
than their sisters; therefore, an imbalance of real or
perceived power exists. The third reason is that repeated
direct or indirect acts of aggression are a hallmark of
bullying definitions.36 As with peers, repeated acts of
aggression might not be seen merely as a reaction to
frustration, but as an eort to establish a social hierarchy
and access to resources (eg, attention, love, material
goods), a characteristic of peer bullying traced across
societies and time.37 Environments that are conducive to
hierarchies (ie, non-egalitarian conditions that reward
getting ahead of others) increase bullying in
classrooms,38,39 at home,33 or even in nations,40 and are
associated with greater stability of bullying with time.41
Depending on the conditions (eg, siblings are not
chosen friends), repeated use of aggression, imbalances
of power, and eorts to seek access to resources, this
aggression between siblings can be thought to be sibling
bullying.
Prevalence of sibling bullying
Few studies exist on sibling bullying or even sibling
aggression more generally. Systematic searches of online
databases show that in the past 25 years, only 19 studies
have predominately focused on bullying behaviour in
siblings. All of these studies fit with the aforementioned
definition, since they take into account physical (eg,
hitting, kicking, pushing), verbal (name calling, threats),
or relational (exclusion, rumour spreading) acts of
aggression between siblings, which are used repeatedly
over time. Most studies rely on child self-reports, and
although some studies also use parental reports,
particularly with younger children, parent reports
probably underestimate the prevalence of sibling
bullying. Parents are probably unaware of every physical
fight between siblings, and might know even less about
indirect bullying, since this is not always disclosed to the
parents, similarly to peer bullying.42
Studies vary greatly in their approach to measuring
sibling bullying, using diering instruments and cuto
points (eg, ever been bullied vs bullying within the past
6 months; table 1). Yet, despite these dierences,
investigators and health-care professionals agree that
sibling bullying is widespread, and experienced by a
large proportion of children and adolescents. When any
form of sibling bullying is measured, prevalence rates
Panel 1: Definition of sibling bullying
Any unwanted aggressive behaviour(s) by a sibling that
involves an observed or perceived power imbalance and is
repeated multiple times or is highly likely to be repeated;
bullying may inflict harm or distress on the targeted sibling
including physical, psychological, or social harm. It
encompasses two modes of bullying (direct and indirect) as
well as four types of bullying (physical, verbal, relational, and
damage to property).
Definition adapted from the Centers for Disease Control and Prevention (Atlanta, GA,
USA) uniform definition of peer bullying.31
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Country Sample Age (years) Measures Prevalence Types of sibling bullying
Duncan (1999)35 USA 375 children; 178 girls,
194 boys; 336 (89·6%)
children with
siblings[A:178+194=372
not 375; please confirm if
3 unknown/no data]
Range 12–14;
mean 13·4
Adapted Peer Relations
Questionnaire
3% of children were victimised pretty
often or very often; 14·6% of children
victimised their siblings pretty often or
very often; 28·6% of children both
victimised and were victimised by their
siblings pretty often or very often
49·1% of victims (including bully–victims)
were picked on or called names, 22% were hit
and pushed around, 8·1% were beaten up;
41·6% of bullies (including bully–victims)
were called names, 30% were picked on,
24·4% hit or pushed around, 11·2% were
beaten up
Wolke and Samara
(2004)2
Israel 921 children; 473 girls,
448 boys; 449 Jewish,
472 Arabic; 898 (97·5%)
children with siblings
Range 12–15;
mean 13·7
(SD 0·9)
Adapted Bullying
Questionnaire
16·5% of children were victimised at least
once a week or more often in the
previous 6 months
6·6% of children were victimised verbally
only, 3·3% physically only, 5·4% physically
and verbally, and 1·2% with all three
types[A:which 3 types?]
Finkelhor et al
(2006)5
USA 2030 children; 50% boys,
76% white
Range 2–7 Juvenile Victimization
Questionnaire
35% of children had been hit or attacked
by a sibling in the past year. Of these
children, 40% were chronically victimised
(more than four attacks per year)
··
Button et al
(2010)43
USA 8122 children; 3704 boys,
4343 girls; 64·7% white
[A:sums to 8047; please
confirm if no data]
Range 12–18 Measure derived by
investigators to assess
types of sibling
aggression
42% of children were victimised within
the previous month
31·3% of victims experienced verbal bullying,
32·5% shoving or pushing, 17·9% punching
or kicking, 12·4% threats, 2·9% weapon
attacks
Wolke and Skew
(2011)44
UK 2163 children; 1078 girls,
1085 boys
Range 10–15;
median 12·5
Sibling Bullying
Questionnaire
16% of children were victimised by
siblings quite a lot or a lot during the
previous 6 months; 4·5% of children
victimised their siblings quite a lot or a lot
in the previous 6 months; 33·6% of
children were both victimised and had
victimised their siblings quite a lot or a lot
over the previous 6 months
30·8% of victims experienced physical
bullying, 29·5% verbal bullying, 25·4%
teasing, and 17·6% stealing; 22·5% of bullies
perpetrated physical bullying, 21·8% verbal
bullying, 21·0% teasing, and 10·1% stealing
Radford et al
(2013)45
UK 6196 children;
2160 parents (for children
aged 0–10 years),
2275 children (11–17 years),
1761 young adults
(18–24 years); 51·6% female
Range 0–24 Modified version of the
Juvenile Victimization
Questionnaire
In their lifetime, bullying by siblings was
reported by 28·4% of children aged
0–10 years, 31·8% of those aged
11–17 years, and 25·2% of those aged
18–24 years
··
Skinner and
Kowalski (2013)46
USA 53 children; 24 boys,
29 girls
Mean 19·15
(SD 1·94)
Adapted from the
Olweus Bullying
Questionnaire
78% of children were victimised once or
more during childhood, 13% 2–3 times
per month, 17% once a week, 15% several
times per week; 85% of children had ever
victimised their sibling during childhood,
26% 2–3 times per month, 11% once a
week, 13% several times per week
83% of victims experienced verbal bullying,
69% physical bullying, 66% exclusion;
91% of bullies perpetrated verbal bullying,
72% physical, 61% exclusion
Tucker et al (2013)30 USA 1705 children; 51% boys,
63% white
Range 0–17 Adapted from the
Juvenile Victimization
Questionnaire
37·6% of children experienced at least
one incident of victimisation by siblings
in the previous year
32·3% of victims experienced physical
bullying, 9·8% property-based bullying,
2·7% psychological bullying
Bowes et al (2014)47 UK 6928 children; 3692 girls,
3236 boys
Range 11–15;
mean 12·1
(SD 9·5)
Adapted Bullying
Questionnaire
47·4% of children were victimised in the
previous 6 months, 30·3% were regularly
victimised (2–3 times per month or more
often)
··
Tippett and Wolke
(2014)1
UK 4237 children; 49·3% boys Range 10–15;
mean 12·52
Sibling Bullying
Questionnaire
45·8% of children were victimised quite a
lot or a lot during the previous 6 months;
36·5% of children perpetrated bullying
quite a lot or a lot during the previous
6 months; significant correlations
(p<0·001) shown between all forms of
victimisation and perpetration
suggesting many children were sibling
bully–victims
28·1% of victims experienced physical
bullying, 26·5% verbal bullying, 23·5%
teasing, and 17·1% stealing; 20·4% of bullies
perpetrated physical bullying, 20·3% verbal
bullying, 19·6% teasing, and 9·9% stealing
Tucker et al (2014)48 USA 1726 children; 51% boys;
58% white
Range 0–17 Adapted from the
Juvenile Victimization
Questionnaire
47% of children experienced
victimisation by siblings within the past
year
··
Tanrikulu and
Campbell (2015)49
Australia 455 children; 262 girls,
177 boys
Range 10–18 Adapted from the
Traditional Bullying and
Cyberbullying
Questionnaire
13·6% of children had victimised their
siblings in the past year; 25·4% of children
had victimised and been victimised by
their siblings in the past year
12·5% of bullies perpetrated traditional
bullying, 0·4% cyberbullying, and 0·7% both;
19·1% of bully–victims experienced
traditional bullying, 0% cyberbullying, and
6·3% both
Table 1: Summary of studies describing prevalence of sibling bullying
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Country Sample Age (years) Family factors Significant associations
Hardy (2001)58 USA 203 children; 52 boys,
151 girls; 74·9% white
Range 17–48;
mean 21·21
(SD 5·43)
Structural factors: family constellation,
number of siblings
Adult or caretaker behaviour: family
cohesion, family stress
Structural factors: no association was found with rates of sibling
aggression
Adult or caretaker behaviour: experience of family stress was associated
with both sibling victimisation (p<0·001) and perpetration (p<0·05)
Updegraff et al
(2005)59
USA 185 sibling pairs; 99
boys and 89 girls (older
siblings); 94 boys and
94 girls (younger
siblings)[A:how do the
numbers work here?]
Older sibling:
mean 16·0
(SD 0·7);
younger
sibling: 13·5
(1·0)
Adult or caretaker behaviour: parental
warmth, parental involvement, differential
treatment
Higher rates of relational aggression between siblings were associated
with less maternal warmth (p<0·001), less paternal warmth (p<0·001),
and less paternal involvement (p<0·05); younger siblings reported less
relational aggression when they felt older siblings were not treated
differently and this was associated with maternal warmth (p<0·01) and
paternal warmth (p<0·01)
Yu and Gamble
(2008)60
USA 433 families (mothers
and older–younger
sibling dyads)
Younger child:
mean 11·6
(SD 1·8); older
child 14·3 (2·1)
Adult or caretaker behaviour: family
cohesion, differential treatment, maternal
psychological control
Negative and less cohesive family environments predicted greater
aggression between siblings, specifically overt aggression (p<0·001) and
relational aggression (p<0·001); maternal psychological control was also
associated with greater sibling aggression, specifically overt aggression
(p<0·001) and relational aggression (p<0·01)
Eriksen and Jensen
(2009)6
USA 994 parents Range 0–17 Structural factors: biological or adopted
or stepchild, parental divorce or
separation, percentage of male children,
time in house or neighbourhood, years
married or together
Socioeconomic factors: parental
employment, parental education, family
income, financial concerns
Adult or caretaker behaviour: household
equality, partner violence, parent-to-
child violence, parental temperament,
marital satisfaction, use of physical
punishment
Experience of less severe sibling violence (defined as hitting and minor
injurious forms of physical contact) was associated with more male
children (p<0·01), less time lived in house (p<0·05), fewer years married
(p<0·001); higher rates of sibling violence were found in households with
lower family incomes (p<0·01); characteristics which increased the
likelihood of sibling violence included more parent-to-child violence
(p<0·001) and wife loses temper more easily (p<0·01)
Button and Gealt
(2010)43
USA 8122 children;
3704 boys, 4343 girls;
64·7% white
Range 12–18 Adult or caretaker behaviour: child
maltreatment and domestic violence
Greater likelihood of sibling victimisation was associated with higher
levels of child maltreatment (p<0·05) and domestic violence (p<0·05)
Menesini et al
(2010)55
Italy 195 children; 98 boys,
97 girls
Range 10–12 Structural factors: age of siblings, sex of
siblings
Having male siblings was associated with more bullying perpetration
(p<0·05) and victimisation (p<0·001); children with older siblings were
more often victimised (p<0·001); a sex-by-age interaction was found,
with boys more often bullying younger siblings, whereas girls bullied older
siblings (p<0·05)
Miller et al (2012)61 USA 150 mother–child dyads Range 3–5·5 Adult or caretaker behaviour: intimate
partner violence, adult-to-child
aggression, violent television viewing,
maternal depression
Greater rates of sibling aggression were associated with maternal
depression (p<0·01) and watching more violent television (p<0·01)
Radford et al (2013)45 UK 6196 total:
2160 parents
(for 0–10 year olds),
2275 children (aged
11–17 years), 1761
young adults
(18–24 years); 51·6%
female children
Range 0–24 Adult or caretaker behaviour: parental
maltreatment
Any experience of maltreatment by a parent or guardian was associated
with an increased risk of victimisation by siblings for all age groups
(<11 years odds ratio 1·26 [p<0·05], 11–17 years odds ratio 1·56 [p<0·001],
and 18–24 years odds ratio 1·77 [p<0·001])
Tucker et al (2013)30 USA 1705 children; 51%
boys, 63% white
Range 0–17 Structural factors: sex of siblings, age of
siblings, sibling relative age
Socioeconomic factors: parental education
Higher rates of sibling victimisation were reported in male–male sibling
pairs (p<0·05); less victimisation was found among siblings with a large
age gap (of 5 or more years) when compared with those only 1 year apart
(z=–1·99); living with parents who had any level of college education
increased the risk of sibling victimisation (compared with parents who
attended only high school or less; z=2·39)
Bowes et al (2014)47 UK 6928 children; 3692
boys, 3236 girls
Range 11–15;
mean 12·1
(SD 9·5)
Structural factors: birth order, parental
divorce or separation, number of
children, gender of siblings
Socioeconomic factors: social class,
maternal education
Adult or caretaker behaviour: child
maltreatment, domestic violence,
maternal depression
Greater rates of sibling victimisation were associated with being the
younger child (p<0·001), having more than three children (p<0·001), and
having an older brother (p<0·001); slightly more sibling victimisation was
observed among low social class families (p=0·05); sibling victims
experienced greater domestic violence (p<0·001), maltreatment by an
adult (p<0·001), and maternal depression (p<0·001)
(Table 2 continues on next page)
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vary from about 15% to 50% for victimisation by siblings,
and 10% to 40% for perpetrating sibling bullying. This
prevalence rate is higher than in studies of peer bullying,
which usually show between 5% and 20% of children to
be victimised, and 2–20% to bully others.50 Direct
comparisons show a higher frequency of sibling than
peer bullying.33,35,48
A unique aspect of sibling bullying is the high
prevalence of bully–victims, children who are both
victimised by their siblings, but also bully them.1,33,35 Most
children involved in sibling bullying fall into this
category, which diers distinctly from peer bullying, in
which children tend to adopt stable victim or bully roles
(although these distinctions decline with age)51,52 with
only few of these children identified as peer bully–
victims.50 The ability to change between roles in sibling
relationships might be evidence of a more fluid power
dynamic, whereby siblings use their familiarity to gain
an advantage over each other. Thus, they are less likely to
become confined to being only victims or only bullies.
The behaviours involved in sibling bullying closely
resemble those of peer bullying, with most children
reporting several physical, verbal, or relational
behaviours.1,35,43,44 Similarities also exist regarding age and
sex variations. As with peer bullying,53,54 incidence of
sibling victimisation and bullying perpetration shows
some decline with age, particularly in physical
aggression.1,6,49 Boys are more likely to perpetrate acts of
sibling aggression, although no clear gender dierences
regarding victimisation have been shown.1,35,44,55 Although
these characteristics show individual associations, the sex
and age composition of the sibling relationship can have
a pronounced eect on overall rates, with more sibling
bullying reported in male–male30 or older male–younger
female sibling dyads.55
Overall, results from both national surveys and
opportunistic studies in the USA, UK, Italy, Israel, and
Australia suggest that sibling bullying is the most frequent
form of maltreatment, more so than by parents, adult
strangers, or peers.5,45,56,57 As a result, relationships with
siblings are probably the most aggressive relationships that
the majority of children will ever encounter during their
childhood.
Family factors associated with sibling bullying
Household and family characteristics might have some
eect on rates of aggression, since they are the primary
environment in which siblings interact. Several studies
(table 2) have explored these associations. Household or
family characteristics can be broadly grouped into three
categories: structural factors, which include household
composition, number, age, and sex of siblings; socio-
economic factors, which include household income and
parental education and occupation; and adult or
caretaker behaviour, such as child maltreatment and
parenting behaviour. The composition of the household
has some eect on rates of sibling victimisation and
bullying perpetration. Consistent with self-reports,
overall rates of sibling bullying are higher in households
with male siblings,1,6,30 and younger children tend to
experience more victimisation, often because of an older
sibling.47,55 In support of Levy’s hypothesis,20 some
studies showed that sibling bullying took place more
often in siblings who were close in age (less than a year
apart).30 Furthermore, as the number of children within
a household increases, so does the rate of sibling
bullying.1,47 With the exception of one study,62 no studies
have shown that single-parent or step families have
increased risk of sibling bullying.
Few studies have examined the association between
socioeconomic characteristics and sibling bullying,
despite evidence showing greater rates of any intra-
familial violence in families with low socioeconomic
status than in those with high socioeconomic status.6,57
Results are mixed. Although higher rates of aggression
have been seen in low-income families6 or those with
financial stress,1 higher parental education also predicts
more sibling bullying.1,30,62 Similar to results on peer
Country Sample Age (years) Family factors Significant associations
(Continued from previous page)
Tippett and Wolke
(2014)1
UK 4237 children; 49·3%
boys
Range 10–15;
mean 12·52
Structural factors: number of siblings, sex
of siblings, birth order, parental divorce or
separation
Socioeconomic factors: parental
qualification, household income, poverty,
deprivation, financial stress
Adult or caretaker behaviour: parent–
child relationships, parenting behaviour
Greater rates of victimisation and perpetration of sibling and aggression
were associated with having more than one sibling (p<0·001), having all
male siblings (p<0·05), and being the eldest sibling (p<0·05); experience
of sibling aggression as both a victim and perpetrator was associated with
moderate to high parental education (for university or higher, p<0·05),
and greater financial stress (p<0·05); characteristics that predicted greater
sibling aggression included poor parent–child relationships (p<0·001),
harsh parenting behaviour (p<0·001)
Tucker et al (2014)48 USA 1726 children; 51%
boys; 58% white
Range 0–17 Structural factors: biological or single or
step family;
Socioeconomic factors: parental education
Adult or caretaker behaviour: parental
warmth, parental supervision,
inconsistent or hostile parenting, exposure
to family violence, parental conflict
Children in step families experienced more sibling victimisation overall
(odds ratio 1·96, p<0·01), whereas children in single parent families
reported more severe victimisation (2·50, p<0·01); higher parental
education predicted more sibling victimisation (1·56, p<0·001 for any
college education vs none); more victimisation was associated with
parental inconsistency or hostility (1·15, p<0·001), less parental
supervision (0·72, p<0·05), and witnessing family violence (1·60, p<0·05)
Table 2: Summary of studies describing associations between family factors and sibling bullying
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victimisation,63 sibling bullying is frequent in families of
all social strata.
Cultural dierences have also been shown in
comparisons between native-born and immigrant
children in the USA. Immigrant siblings spent more
time together, were more intimate, and provided greater
social support,59,64,65 whereas native-born siblings showed
greater conflict and bullying.6,7,30 How cultural dierences
interact with other societal characteristics such as
socioeconomic status or parenting behaviour to aect
sibling relationships is unclear.26
The most consistent associations of family factors
aecting sibling bullying have been identified to be adult
or caretaker behaviours. Child maltreatment or adult-to-
child violence increases the risk of sibling victimisation
and bullying perpetration.6,43,45,47 Similarly, absence of
parental warmth,59 harsh parenting,1 and low supervision59,62
have been linked with more bullying between siblings.
Studies on general sibling conflict66,67 and on sibling
bullying59 have identified a link with dierential parental
treatment of siblings, suggesting that sibling bullying
might be motivated by inequality and a desire to improve
one’s status, thereby mimicking the motivations that
underlie bullying at school.37
Possible links between sibling and peer bullying
Several theories suggest that interactions within the
family, including sibling relationships, might generalise
to children’s interactions with peers in other contexts,
such as in school.2 Social learning theory suggests that
children learn particular behaviours in relationships with
their parents and siblings and that these behaviours
generalise to their interactions with peers and friends.68,69
Attachment theory proposes that children’s relationships
with peers and siblings are aected by internal working
models of relationships, which are carried forward from
their earliest relationships with attachment figures.70,71
Furthermore, studies suggest that children’s enduring
characteristics, such as temperament, might elicit similar
responses from dierent relationship partners.72 Although
each of these theories implies some transference between
children’s relationships with siblings, friends, and peers,
the proposed mechanisms linking relationships dier.
By contrast, few associations are expected in children’s
familial and extra-familial relationships. First, siblings
growing up in the same context only share, on average,
50% of their segregating genes, and they are subject to
non-shared experiences in the family and to dierential
treatment by their parents.73 Second, children in peer
relationships are from dierent families and might have
dierent temperamental characteristics, interests, and
talents. Their previous experiences in relationships vary
and their beliefs and expectations about how to behave in
relationships probably also dier. Finally, societal norms
and culturally held beliefs about how children should
behave in particular relationships, such as sibling
relationships compared with best friendships, encourage
dierences and might decrease the likelihood of
associations between them.74 Indeed, the pattern of
results has been inconsistent with no simple carry-over
from sibling relationships to friendships.74 However, this
might be dierent for adverse sibling experiences such
as sibling bullying. Studies that have investigated the
relationship between sibling and peer bullying are shown
in table 3.
Two studies examined only sibling victimisation2,48
whereas other studies examined bullying perpetration and
victimisation in siblings and their relationship to peer
bullying.1,35,55 First, all results lend support to a carry-over
from sibling bullying to involvement in peer bullying.
Second, where studied, the results suggest a homotypic
(ie, same role in sibling and peer bullying) carry-over
across contexts1 and this might apply more for boys than
for girls.55 However, as aforementioned, most children
involved in sibling bullying get victimised and retaliate
(bully–victims). The two studies that provided statistics
investigated only sibling victimisation and perpetration.
Not surprisingly, these were highly correlated. More
studies are needed, but the evidence lends support to the
theory that adverse sibling relationships transfer to similar
experiences in peer relationships.
All studies were cross-sectional investigations and do
not allow for causal interpretations. Longitudinal studies
are necessary to conclude that sibling bullying is a
precursor of peer bullying. One innovative study
combined direct examination of sibling-directed
antisocial behaviour in the family’s homes at 3 years and
6 years with interaction of unfamiliar peers in an
experimental setting.75 Antisocial behaviour between
siblings was assessed at home when the children were
3 years and 6 years old, and at 6 years, they were invited
to the laboratory where they were paired with two other
unfamiliar children for a triadic play situation. Those
young children who showed high sustained antisocial
behaviour towards their siblings (at 3 years and 6 years)
were more likely to bully or refuse to share or interact
with unfamiliar peers. Thus, at least in young children,
experiences with siblings are predictive of aggressive
behaviour towards unfamiliar peers.
Sibling bullying, and emotional and behavioural
difficulties
If we consider that sibling bullying is widespread, the
crucial question is whether it has any adverse emotional
or psychiatric outcomes or is just an event without
consequences. As shown in table 4, five cross-sectional
studies and one prospective study specifically
investigated the relation between sibling bullying and
emotional problems. Four of five studies showed highly
raised depression and loneliness scores35 and more
behavioural problems within the clinical range using
the Strengths and Diculties Questionnaire,2,44 a
reliable and valid screening questionnaire for
psychiatric problems in childhood and adolescence76,77
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or increased mental distress.78 Three of the studies also
reported that (1) the associations with behavioural
problems were stronger with more severe sibling
victimisation (ie, involved both verbal and physical
bullying,2 or mental distress was higher with increased
severity of the physical assault78) or (2) the odds of
behavioural problems were increased up to 14 times if
the child was bullied at home and by peers at school.2,44
The eects of sibling and peer victimisation were
additive rather than interactive in the survey from the
USA.78 Whenever investigated, results suggest that
children who were both victims and bullies (sibling
bully–victims) were at higher risk of behavioural
problems than children who were only victimised. No
increased risk was seen for bullies.2 By contrast, the UK
survey45 of maltreatment showed only increased mental
distress (reported by the parents) in relation to sibling
victimisation in children aged 0–9 years, but not in the
self-reports of adolescents or young adults. The two
aforementioned national maltreatment surveys45,78 in
the USA and the UK showed two other important
results in multivariate regression analyses. First, the
USA survey identified that sibling bullying
independently predicted mental distress as much as
child maltreatment and more than sexual victimisation
by adults.78 Second, both USA and UK surveys showed
that peer victimisation had stronger associations with
mental distress than maltreatment by adults.47,79,80
The cross-sectional studies do not enable the
interpretation of the direction of eects. Children who
have emotional or behavioural problems might be more
likely targets of sibling bullying. A large prospective
study of peer and sibling bullying recruited mothers in
pregnancy, and regular assessments of child and
parental mental health and peer bullying were carried
out. When the children were 12 years old, they completed
a detailed questionnaire about sibling bullying and
mental health (depression, anxiety diagnoses), and self-
harm experiences were assessed at 18 years of age.47 This
study showed that after controlling for several family
Country Sample Age (years) Sibling bullying Peer bullying Sibling to peer bullying association
Duncan (1999)35 USA 375 total children;
178 girls, 194 boys;
336 (89·6%) with
siblings[A:same
question here]
Mean 13·4 Of 336 children, 186 (55·4%)
experienced no sibling
bullying, 10 (3%) were victims,
49 (14·6%) were bullies,
91 (28·6%) were bully–victims;
classification used was pretty
often or very often
Of 373 children,
207 (55·5%) experienced no
sibling bullying, 60 (16·1%)
were victims, 72 (19·3%)
were bullies, 34 (9·1%) were
bully–victims; classification
used was pretty often or
very often
60% of peer bully–victims reported being bullied by
their brothers or sisters; most peer–bully victims
(76·7%) and peer bullies (56·5%) reported that they
bully their siblings; less than half of the peer victims
(38·2%) and peer not involved (32·1%) reported
bullying their siblings (no significance tests done)
Wolke and Samara
(2004)2
Israel 921 children;
473 girls, 448 boys;
449 Jewish,
472 Arabic;
898 (97·5%)
with siblings
Mean 13·7 Of 898 children, 152 (16·9%)
were victims (3·3% physically
only, 6·6% verbally only, 5·4%
both); classifications used were
every week or several times per
week
Of 921 children,
145 (15·8%) were victims
and 120 (13·1%) bullies or
bully–victim; classification
used was every week or
several times per week
152 children were victims at home, 77 (50·7%) were
also victims at school, by contrast to only 95 (12·4%)
of 769 non-victims at school (odds ratio 7·3, 95% CI
4·9–10·6); the study did not ask about sibling
bullying perpetration
Menesini et al
(2010)55
Italy 195 children with
siblings 4 years older
or younger (selected
from 562); 97 girls,
98 boys
10–12 years Prevalence not reported Prevalence not reported The correlations between the victimisation and
bullying scales were 0·32 in boys and 0·44 in girls for
sibling bullying victim–peer bullying victim, 0·24 in
boys and 0·39 in girls for peer bullying bully, 0·50 in
boys and 0·27 in girls for sibling bullying bully–peer
bullying bully, and 0·04 in boys and 0·41 in girls for
peer bullying victim; sibling bullying victimisation
and sibling bullying were highly correlated (r=0·69)
suggesting that most children were both
perpetrators and victims
Tippett and Wolke
(2014)1
UK 4899 children;
4237 (87%)
with siblings
10–15 years Of 4237 children, 45·8% were
victimised, 36·5% perpetrated
bullying; classification used
was quite a lot or a lot during
last 6 months
Of 3906 children,
416 (10·7%) were victims,
98 (2·5%) were bullies,
34 (0·9%) were
bully–victims; classification
used was quite a lot or a lot
in previous 6 months (data
not reported)
Homotypic association between roles in sibling
bullying and peer bullying with victims (odds ratio
1·69), bullies (2·63), and peer bullying bully–victims
(3·44)
Tucker et al
(2014)48
USA 3059 children (with
at least one sibling
<18 years); 51% boys;
58% white
3–17 years; split in
two groups for
analysis: 3–9 years
(1536 children),
10–17 years
(1523 children)
15% victimisation of children
by sibling, 33% by sibling and
peer; 14% victimisation of
adolescents by sibling, 15% by
sibling and peer; classification
used was any victimisation in
previous year
12% victimisation of
children by peer, 33% by
peer and sibling; 22%
victimisation of adolescents
by peer, 15% by sibling and
peer; classification used was
any victimisation in
previous year
Sibling victimisation was associated with peer
victimisation (analysed by logistic regression) in
childhood (odds ratio 1·41, CI 1·11–1·80) and
adolescence (1·88, 1·47–2·42); study was controlled
for several potential confounders including child
maltreatment, witnessing community and family
violence
Table 3: Summary of studies of the association between sibling and school bullying
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factors, pre-existing behaviour, emotional problems,
peer bullying, child maltreatment by adults, and
domestic violence in the household, sibling bullying
independently increased the risk of clinical depression
and self-harm by about two times (table 4). Furthermore,
a dose–response relation was identified, as shown by a
linear trend: with increasing exposure to sibling
bullying, the odds of mental health problems in young
adulthood increased. Together, these results suggest a
causal relationship between sibling bullying and
subsequent mental health problems.
Balanced sibling relationships
Just as in relationships between friends, occasional
conflict and disagreement between siblings is normal.
Some studies suggest that small amounts of sibling
conflict and their resolution might even have some
beneficial eects on child development. Balanced sibling
relationships, in which children experience both conflict
and support, have been associated with the development
of better social–emotional skills, including perspective-
taking, and the ability to understand and talk about
emotions.8,81–83 Associations have also been shown with
peer relationship quality, whereby having a balanced
sibling relationship, comprising equal amounts of
conflict and support or warmth, promotes greater social
competence and can lead to better quality friendships
with peers.84 Indeed, occasional conflict in non-dominant
sibling relationships has been reported to predict less
peer victimisation, which might be attributable to
children acquiring and practising conflict management
skills at home, and transferring these skills to the school
environment.83,85 Although studies clearly show that
sibling bullying increases the risk of behavioural and
Investigators Country Sample Age Mental health
instrument
Associations with behavioural or emotional difficulties
Duncan
(1999)35
USA 375 children; 178 girls, 194 boys;
336 (89·6%) with siblings
Mean 13·4 years
(7–8 graders)
Multi-score Depression
Inventory for Children
(MDIC); Children’s
Loneliness
Questionnaire (CLQ)
Since most siblings involved in any bullying were bully–victims, all subgroups
were collapsed into a group of 150 siblings involved in bullying, which had
highly raised scores in overall depression (MDIC), higher loneliness scores (CLQ),
and a significant sibling involvement by peer involvement interaction (those
who were bully–victims at school and involved in bullying at home had the
highest level of psychopathological difficulties; those not involved at home or
at school had the lowest psychopathological disorders and loneliness)
Wolke and
Samara
(2004)2
Israel 921 children; 473 girls, 448 boys;
449 Jewish, 472 Arabs; 898 (97·5%)
had siblings (median 3)
Mean 13·7 years
(SD 0·9);
(7–9 graders)
Strength and Difficulties
Questionnaire (SDQ)
Severity of total difficulties: 16% of children had none, 31% physical or verbal,
57% both
Severity of hyperactivity conduct disorder (defined borderline/clinical range as
>80th percentile): 13% none, 34% physical or verbal, 56% both
Context of total difficulties: 16% none, 24% school or home, 46% both
Context of hyperactivity conduct disorders: 12% none, 22% school or home,
52% both
Wolke and
Skew (2011)44
UK Representative sample from Household
Panel; 2163 children; 1872 (87%) had
siblings, 57% with both biological
parents, 29% one biological parent, 13%
step-parent, 2% no biological parent;
87% were biological siblings, 10% half-
sibling, 3% step-sibling; 40% oldest
sibling, 23% middle or co-twin, 38%
youngest
Median
12·5 years;
range 10–15
SDQ; Overall
Unhappiness Scale
Relation between sibling bullying roles and SDQ total difficulties clinical range
(>90th percentile; adjusted for school bullying) significant for bully–victims
(odds ratio 3·2 [95% CI 2·2–4·7]), but not for bullies (2·1, 0·9–5·0) or victims
(1·7, 0·9–3·0)
Relation between bullying victimisation (victims or bully–victims) by siblings or
school peers and SDQ total difficulties (clinical range) or total unhappiness
measure (clinical range) adjusted for confounders: SDQ adjusted OR 2·7 (1·8–
4·1), unhappiness 2·2 (1·5–3·1); by sibling and school peers: SDQ adjusted OR
14·1 (8·4–23·5), unhappiness 10·5 (6·6–16·7)
Radford et al
(2013)45
UK 50 000 households contacted
(64% response rate in households with
children or young people); 2160 parents,
2275 young people and their parents,
1761 young people
2 months
to 10 years;
11–17 years;
18–24 years
Trauma Symptom
Checklist (versions for
young children, children,
and adults)
Sibiling victimisation had statistically significant but low association with
reported trauma scores in childhood. No association was found for adolescents.
Peer victimisation had consistent and strong associations with trauma scores in
multivariate models (controlling for other forms of maltreatment and
poly-victimisation). These associations exceeded those for the second best
predictor, which was maltreatment by parent of guardian
Tucker et al
(2013)78
USA National Children’s Survey of Exposure
to Violence; 3599 children; 51% boys;
63% white
0–9 years
(parental
report),
10–17 years
(self-report)
Trauma Symptom
Checklist for Children;
version for young
children (parents);
version for older
children (self-report);
total scores were
standardised
Mean Mental Health Scores were higher (suggesting more distress) in children
and adolescents who experienced physical assault than in children who did not
with no weapon of injury (0·21 vs 0·01), physical assault with weapon of injury
(0·47 vs 0·07), property victimisation (0·29 vs 0·06), or psychological
victimisation (0·49 vs 0·07). Scores adjusted for parental education level,
ethnicity, language, child gender, all non-sibling victimisation by others
(parents, strangers, internet), and witnessing family or community violence
Bowes et al
(2014)47
UK Longitudinal study with 6928 children;
3692 girls, 3236 boys
12 years for
sibling bullying;
18 years for
mental health
outcomes
Clinical Interview
Schedule-Revised;
ICD-10 diagnoses of any
depression; any anxiety
disorder; self-harm
The results suggest a significant linear trend with increased odds of depression
disorder and self-harm at 18 years with increasing severity of sibling
victimisation at 12 years. Children victimised by their siblings several times a
week had depression (odds ratio 1·85, 95% CI 1·11–3·09) and self-harm: (2·26,
1·40–3·66). Study was adjusted for pre-existing psychiatric disorder, family
factors, and peer victimisation at 8 years
Table 4: Sibling bullying, and behavioural and emotional difficulties in childhood to early adulthood
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mental health problems, occasional conflict, as part of a
balanced, supportive, and involved sibling relationship,
provides opportunities for constructive resolutions of
conflicts that can have some positive benefits on
children’s emotional and social development.8
Harms caused by widespread sibling bullying
Despite the accumulating evidence of how widespread
sibling bullying is and its adverse eects, little scientific
research on it exists. Some investigators suggest that this
paucity can be traced to the general discounting of the
frequency and seriousness by those individuals who
most aptly could intervene at an early stage. As Krienert
and Walsh state, “The age old adage ‘Kids will be kids’
seems to have led to a pervasive belief that aggression
and bullying between brothers and sisters is a rite of
passage and thus likely rarely investigated”.7 For example,
although the act of being hit or shoved from a chair in
the oce would lead to alarm and possible police
involvement if done by a stranger, the same act may just
attract a mild response by some parents at home.33 Why
do we assume that if it is done by a stranger it is harmful
but if it is perpetrated repeatedly by a sibling it has no ill
eects? Why is there a belief that because it is so frequent
it does not need any intervention? In other frequent
disorders, no doubts exist that prevention and treatment
are necessary. The lifetime risk of any fracture has been
shown to be 53·2% by the age of 50 years in women, and
20·7% at the same age in men.86 Bone fractures occur
frequently but nobody suggests that because they are
frequent that they can be left untreated and do no harm.
Although many of the scars are psychological, the scars
of sibling bullying can also include physical injury, which
is often underreported and underrecorded.7
In reaction to a press release and report of our
prospective sibling bullying study,47 the BBC News
received so many emails and letters from the public
reporting on their experiences of sibling bullying and how
it has aected their life that they ran a magazine story
using readers’ experiences of sibling bullying (panel 2).
Interventions
At the time of writing, no interventions have been
tailored to treat or prevent sibling bullying specifically.
However, several interventional programmes have been
developed that focus on improving sibling relationship
quality by fostering socio-emotional competencies,
emotion regulation abilities, interpersonal skills, and
oering parental guidance on how to intervene and
mediate disputes or conflicts between their children.
These general sibling interventions have reported
positive eects on both parents and their children and the
quality of sibling relationships (table 5). They integrate
many aspects of behavioural and communication
interventions, ranging from reinforcing positive
communication and behavioural modelling, to the use of
video clips guiding parents and children to understand
and find solutions for conflicts. Parents are often
perceived as the co-therapists of how to manage and
moderate fights and conflicts.87 In view of the consistent
results of parenting being associated with sibling
bullying, evidence-based eective mediation strategies
for parents that encourage children to vocalise and seek
out conflict resolutions, become more aware of their
siblings’ perspectives, think about their feelings, control
emotions and impulses, and identify common ground88
might be promising approaches for the development of
intervention packages that deal with sibling bullying.
Although some of these principles are part of inter-
ventions, they have not been suciently assessed. An
alternative approach is to improve the wellbeing of the
victims of sibling maltreatment and reduce negative
emotional consequences by strengthening their family
relationships and enhancing their self-esteem using
assertiveness training and cognitive restructuring, rather
than focusing on the sibling relationships.89
Clinical treatment approaches using case examples or
small assessment studies have been undertaken for
maltreated children placed in foster homes94 or children
who have experienced sibling abuse.95,96 One such
programme, the Promoting Sibling Bonds,94 was used for
maltreated children and might provide an innovative
integrated intervention model for children bullied by
siblings in regular families. Promoting Sibling Bonds
integrates emotional regulation, social learning, family
systems approaches, and parental mediation to deal with
sibling conflict.
In view of how widespread the problem of sibling
bullying is in all types of families, the use of social media
and healthy game approaches (eg, via the internet) that can
reach all families might be considered in future prevention
or intervention programmes for siblings and their parents.
Future investigation
Studies on sibling bullying, its precursors, and its
consequences are few, with as far as we know only one
prospective study on the eects of sibling bullying. More
studies are necessary and funding bodies need to hear
the voices of those who have been aected by sibling
bullying. First, as shown in this Review, enough evidence
Panel 2: BBC News Magazine story: Sibling bullying: “I wished I hadn’t been born”
Kathy, UK: I was bullied by my older brother throughout my childhood. He was 8 years older
and put a lot of energy into bullying. He drew scary pictures on the wall near my bed when I
was 3 years old. He used a soldering iron to write a horrible message—“you are a fat pig”—
on a school pencil case my Mum made for me. At age 11 years, I remember wishing that I
hadn’t been born. I stopped speaking to him at home for two years. My parents did very
little to stop it. Christmas was always ruined by it. I was also bullied at school but it wasn’t as
bad as the bullying at home. I had depression for many years and have experienced
workplace bullying and domestic violence. I know it is all connected to my childhood.
[A: I have requested permission from the BBC. We shall see what they say. We can link
to the article as a reference, but we need permission to reproduce this amount of text]
For the BBC story see
http://www.bbc.co.uk/news/
magazine-24867267
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Country Number
of
children
Intervention Participant
details
Duration and
frequency of
intervention
Control group Training techniques used Results
Kramer
and Radley
(1997)97
USA 42 Fun With
Brothers and
Sisters
4–6 year old
children with
siblings under
30 months
Four weekly 40 min
sessions on campus;
one 30 min final
session at home
Group
discussions,
books, and
videotapes
Social skill training via instruction,
modelling, rehearsal, performance
feedback, and generalisation
training
Mother reports showed less rivalry (p<0·05)
and more warmth (p<0·01); father reports
showed less status or power differential with
time (p<0.06) and less rivalry or competition
(p<0·05). Children who were rated as getting
along better were more likely to display
taught social skills, ie, children rated by
mothers as displaying more warmth such as
increased perspective-taking (p<0·05) and
initiation of sibling play (p<0·10).
Intervention rated as helpful by 70% of
children in intervention group versus 30% in
control group
Smith and
Ross
(2007)88
Canada 48 Parental
mediation
training
Sibling pairs
aged
5–10 years
One session lasting
1·5 h involving
parents only
Use of conflict
checklist to
record home
conflicts
The four stages of mediation
process were taught; use of positive
communication skills was taught;
videotape of mother undertaking
mediation was shown and
information handouts on
mediation were provided; use of a
conflict checklist was
encouraged[A:correct to add “was
encouraged?]
Parental reports showed improvement in
their children’s conflict tactics compared with
control (p<0·01). Children complained more,
but also did every positive behaviour more
often than control (p<0·01). Conflicts in
mediation group were more likely than
expected to be resolved with compromise and
reconciliations (p<0·01). Children in
mediation group more likely to resolve
conflicts versus parents more likely to resolve
in control (p<0·01). Children in mediation
talked more about negotiation and identified
more issues (p<0·05). Home Conflict
Interview showed that children in mediation
more concordantly identified sibling’s
perspective (p<0·05). Negotiation Interview
showed that children in mediation more
concordantly identified sibling’s perspective
(p<0·01)
Kennedy
and
Kramer
(2008)89
USA 95 More Fun With
Brothers and
Sisters
Sibling pairs in
the age range
of 4–8 years
[A:how many?]
Weekly 1 h sessions
in laboratory
playroom; one final
session at home
Pre-test and
post-test;
intervention
given after
experiment
Emotional or social competencies
training via modelling, role-play,
performance feedback and
coaching, transfer of training.
Parents observed and received
guidelines
Parental reports showed increased warmth
(p<0·05), decreased agonism (p<0·001), and
less rivalry or competition (p<0·05).
Observation showed increased warmth and
more involved positive interactions (p<0·05)
and improved regulation of negative affect by
parents decreased for both elder-born
(p<0·001) and later-born siblings (p<0·01)
Feinberg
et al
(2013)90
USA 256 Siblings Are
Special
(feasibility
study)
Sibling dyads
with 5th
grader and
younger
sibling in
2nd–4th grade
12 weekly 1·5 h
after-school
sessions; three 2·5 h
family night
sessions
Received
popular
parenting book
on avoiding
sibling rivalry
Fostering interpersonal skills and
parents’ involvement in sibling
relationship via active games,
written exercises, role-playing, and
discussions
High engagement; average attendance rate
was 88%. Group leaders on average rated
programme usefulness above scale midpoint
(based on 1–5 rating scale). 88% mothers and
81% fathers rated at least one of six methods
as somewhat useful. Fidelity ratings by group
leader and observers were high
Feinberg
et al
(2013)91
USA 348 Siblings Are
Special
Sibling dyads
with 5th
grader and
younger
sibling in
2nd–4th grade
12 weekly 1·5 h
after-school
sessions; three 2·5 h
family night
sessions
Received
popular book on
parenting
siblings[A:same
book as in
Feinberg 2013
(ref 90)?]
Fostering interpersonal skills and
parents’ involvement in sibling
relationship via active games,
written exercises, role-playing, and
discussions
Mothers reported more fair-play (p<0·05),
fewer internalising difficulties (p<0·05);
mothers and fathers reported more self-control
(p<0·05) and more parental non-involvement
(p<0·05); teachers reported more social
competence (p<0·01) and better academic
performance (p<0·05); observers reported
more sibling positivity (p<0·05)
Osarenren
and Ajaero
(2013)92
Nigeria 180 Cognitive
restructuring
and
assertiveness
training
Students from
three public
co-educational
junior
secondary
schools
Five treatment
sessions spread over
5 weeks each lasting
1 h
Students were
given a career
talk
Cognitive restructuring: taught that
absence of self-worth is caused by
negative thoughts; cognitive
restructuring package designed to
help modify and substitute logical
interpretation for self-denigrating
thoughts; assertiveness training
helped teach several different
assertive skills and making students
practise[A:sense okay?]
Cognitive restructuring group had greater
improvements in family relations and higher
self-esteem than control group (p<0·05);
assertiveness training group had higher
self-esteem than controls (p<0·05)
(Table 5 continues on next page)
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warrants additional investigation of sibling bullying, its
precursors, and outcomes. Second, all evidence until
time of writing is from high-income countries such as
Australia, Israel, Italy, UK, or USA. Few studies have
been undertaken in low-income and middle-income
countries. In view of cultural dierences in sibling
relationships, studies in dierent cultures are necessary.
Third, whether reduction of sibling bullying can lead to
reduced peer bullying and reduced mental health
consequences of children needs to be investigated. This
investigation will necessitate the development of
prevention and intervention programmes specifically
addressing sibling bullying and their assessment.
Conclusions
Sibling bullying is widespread with up to 40% of children
being targets of sibling aggression every week or several
times a week.47 Sibling bullying, like peer bullying,63 is not a
problem attributable to poverty, poor parental education, or
single parenting, but is related to parenting quality in all
socioeconomic strata.1 Sibling bullying also increases the
risk of being involved in peer bullying, with sibling victims
more often the target of peer bullying, and sibling bullies
more often bullies or bully–victims at school. Sibling
bullying is associated with concurrent emotional diculties
and distress, and with diagnoses of depression and
increased self-harm in early adulthood. Studies suggest
that children who are bullied both at home and at school
have highly increased emotional diculties compared with
those bullied by peers or siblings only, probably because
they have no safe environment and thus no respite from
bullying. Whenever investigated, studies suggest that early
sibling aggression and bullying is a precursor of adverse
relationships with peers.75 Therefore, to prevent sibling and
peer bullying, intervention needs to start at home.
Although most sibling relationships might involve some
rivalry and conflict between siblings, when the conflict
results in direct physical or indirect psychological
aggression that is repeated with the intent to harm
(bullying), then it necessitates firm and fair intervention by
parents or caretakers. Conflict should be resolved in an
amenable way before it becomes sibling bullying. General
prevention and early interventional trials, including their
assessment, are needed. All clinicians should ask routinely
about sibling bullying.
Contributors
DW generated the idea for the Review. DW, NT, and SD undertook the
scientific literature searches for dierent parts of the Review, read the
articles, and summarised these in tables. DW and NT drafted the
Review and SD reviewed the first version. All authors reviewed the
revised versions.
Declaration of interests
We declare no competing interests.
References
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Country Number
of
children
Intervention Participant
details
Duration and
frequency of
intervention
Control group Training techniques used Results
(Continued from previous page)
Pickering
and
Sanders
(2015)93
Australia 100 Managing and
fighting
aggression
Parents of
3–10 year old
children
experiencing
high levels of
sibling conflict
One 2 h discussion
group session
undertaken with up
to 8–12 parents
Families
continue to
engage using
their usual care
strategies; after
a 6 month
follow-up
session, families
were offered
participation in
same
intervention
Identifying and listing difficulties
the parents currently face and
common reasons for sibling
conflict; parent traps and how to
avoid them; tracking children’s
process using behaviour-tracking
charts; checklist for managing
aggression; diaries of quiet time
and time out; specific sibling
conflict-managing techniques;
discussing potential barriers
Hypothesised outcomes (not yet assessed)
were reduced rates of sibling conflict, lower
rates of ineffective or coercive parenting
strategies, improved child behavioural and
emotional adjustment, and improved parental
confidence and competence
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relevance to sibling bullying, yielding a total of 19 studies. An additional search focusing
on intervention programmes was undertaken using the PsycINFO, PubMed,
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