Heritability of Personality

Abstract

Everything is heritable. Personality is no exception. Personality is hereditary, or passed down from one generation to the next via genetic information, and is therefore heritable. Heritability is the proportion of phenotypic variance in an attribute in a population due to genetic variance in that population. Behavioral genetics research-twin, adoption, and family studies-furnishes the empirical evidence necessary to decipher the relative contributions of genes and environment to personality traits. Although most research in this domain has been done using the Big Five personality constructs, personality traits as defined by different models seem to be heritable. Specifically, they tend to be heritable in the 40-50% range. There is evidence that personality change across age is heritable and that the heritability of traits is consistent across different cultures. Modern technological and methodological advances may allow future research to further delineate which genes predict which personality traits.

Full text

For Review Only
Heritability
Journal:
The Wiley-Blackwell Encyclopedia of Personality and Individual Differences
Manuscript ID
wbepid0052.R1
Wiley - Manuscript type:
Entry
Date Submitted by the Author:
11-Sep-2017
Complete List of Authors:
Maranges, Heather; Florida State University, Department of Psychology
Reynolds, Tania; Florida State University, Department of Psychology
Keywords:
personality, heritability, behavioral genetics, genetics, heredity
Abstract:
Everything is heritable. Personality is no exception. Personality is
hereditary, or passed down from one generation to the next via genetic
information, and is therefore heritable. Heritability is the proportion of
phenotypic variance in an attribute in a population due to genetic variance
in that population. Behavioral genetics research—twin, adoption, and
family studies—furnishes the empirical evidence necessary to decipher the
relative contributions of genes and environment to personality traits.
Although most research in this domain has been done using the Big Five
personality constructs, personality traits as defined by different models
seem to be heritable. Specifically, they tend to be heritable in the 40-50%
range. There is evidence that personality change across age is heritable
and that the heritability of traits is consistent across different cultures.
Modern technological and methodological advances may allow future
research to further delineate which genes predict which personality traits.
The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
Heritability
Heather M. Maranges and Tania A. Reynolds
Department of Psychology, Florida State University
hmaranges@gmail.com
Main body word count: 2,055
Abstract
Everything is heritable. Personality is no exception. Personality is hereditary, or passed down
from one generation to the next via genetic information, and is therefore heritable. Heritability is
the proportion of phenotypic variance in an attribute in a population due to genetic variance in
that population. Behavioral genetics research—twin, adoption, and family studies—furnishes the
empirical evidence necessary to decipher the relative contributions of genes and environment to
personality traits. Although most research in this domain has been done using the Big Five
personality constructs, personality traits as defined by different models seem to be heritable.
Specifically, they tend to be heritable in the 40-50% range. There is evidence that personality
change across age is heritable and that the heritability of traits is consistent across different
cultures. Modern technological and methodological advances may allow future research to
further delineate which genes predict which personality traits.
Abstract word count: 146
Keywords: personality, heritability, behavioral genetics, genetics, heredity
Page 1 of 11 The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
Everything is heritable. This is Turkheimer’s first law of behavioral genetics. Personality
is no exception. Personality can be understood as a person’s characteristic thoughts, emotional
responses, and behaviors. Personality traits are patterns of those relatively enduring
predispositions that influence our behavior across time and situations. Personality is hereditary,
or passed down from one generation to the next via genetic information, and is therefore
heritable. Heritability is the proportion of phenotypic variance in an attribute in a population due
to genetic variance in that population, and personality traits are heritable. This encyclopedia
entry explains what heritability is, briefly describes the methods by which researchers examine
the heritability of traits, and details the extent to which particular personality traits are heritable.
Heritability is the proportion of phenotypic variance that can be attributed to variance in
genetic influence among individuals. A phenotype is the manifested trait of an individual. This
includes height, skin color, and personality. Just as people differ in facial appearance, for
example, so too do they differ in personality. Phenotypic variance can thus be broken down into
two components: genetic influence and environmental influence. Heritability is the former; it is
an estimate of the portion of variance in personality that can be attributed to differences in
people’s underlying genetic makeup.
It is important to note that heritability is an estimate of genetic influence based on the
sampled population (of many individuals); it cannot be estimated from or applied to a single
person. Because heritability is estimated from a group of individuals, its estimated proportion is
dependent upon the variation among those individuals. For example, if the population sampled
differed widely in environments (e.g., some people were from rural Africa, some were from
Beijing, China), the proportion of variance in personality attributable to genes would be lower
than a population of individuals from relatively homogenous environments. When the sample of
Page 2 of 11The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
individuals is from a homogenous environment, there is less variation in their environments,
allowing for more variation in their phenotype to be explained by differences in their genes.
When the sampled individuals are from widely varying environments, on the other hand, this
environmental variation diminishes the proportion of their phenotypic differences that can be
attributed to genetic influence.
Behavioral genetics is a field of research that uses a variety of methods to estimate
heritability. In addition to adoption and family studies, twin studies are a common method. In
these studies, researchers recruit a sample of identical (monozygotic) and fraternal (dizygotic)
twins. Monozygotic (MZ) twins result from the fertilization of one egg (i.e., one zygote), which
then splits into two developing fetuses. Because the two resulting fetuses were formed from the
same egg and sperm, they are genetically identical, sharing 100% of their genes with their co-
twin. Dizygotic (DZ) twins result from the independent fertilization of two eggs by two different
sperm cells. Like regular siblings, dizygotic twins only share 50% of genes in common. Twins,
whether dizygotic or monozygotic, are often raised similarly. That is, they share the same
birthday, parents, house, peers, and neighborhood. Through twin studies, researchers capitalize
on MZ and DZ twins’ similarities in environments with differing levels in genetic relatedness
(100% for MZ, 50% for DZ).
Heritability can be estimated by comparing the phenotypic similarity between MZ and
DZ twins. The more a trait is caused by genes, the more similar MZ twins should appear in that
trait compared to DZ twins. This is because MZ twin have 100% of their genes in common,
while DZ have only 50% in common. The more a trait is caused by the environment, the more
similar MZ and DZ twins should be on that trait (because both MZ and DZ twins experience
relatively similar environments).
Page 3 of 11 The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
The environmental influence on traits can be broken into two subcomponents: shared and
non-shared. Shared environment refers to the environmental factors that twins have in common,
such as parents, neighborhood quality, household income, etc. Non-shared environment refers to
the environmental factors that each co-twin experiences uniquely. For example, one twin (but not
the other) may attend summer camp, experience a tumultuous romantic relationship, or attract a
supportive best friend.
Theorists and behavioral genetic researchers have published much work demonstrating
the extent to which personality attributes in a population can be accounted for by genetic
variance. Notably, thousands of genes contribute to specific traits, and genes combine to
influence overall personality, and, through personality’s interaction with the social world,
happiness and wellbeing (Weiss, Bates, & Luciano, 2008). Temperament, or biologically-based
personality tendencies that are conceptualized as broader than specific traits may be the main
aspects of personality that are influenced by genes. Specifically, the broad patterns of activity
level, sociability, and emotional stability appear to be highly heritable, as evidenced by a review
of behavioral genetic research (Buss & Plomin, 2014).
With respect to specific personality traits, each of the big five personality traits have
heritability estimates around .5 (Bouchard, 2004). Briefly, myriad research has supported the
contention that personality can be captured by five factors, usually conceived as openness,
conscientiousness, extraversion, agreeableness, and neuroticism. Openness is associated with the
common phrases like “open-minded” or “up to try anything new,” and its essence is a divergent
cognitive style that seeks novelty and complexity and links various information.
Conscientiousness involves orderliness and self-control in the pursuit of goals. Extraversion is
associated with positive emotion, exploratory activity, and reward seeking. Agreeableness is
Page 4 of 11The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
more or less synonymous with being kind, sympathetic, cooperative, warm, and considerate.
Neuroticism can be understood as activity of negative emotion systems such as fear, sadness,
anxiety, and guilt.
Genetic variance accounts for about 57% of variance in adult population’s openness, 49%
for conscientiousness, 54% for extraversion, 42% for agreeableness, and 48% for neuroticism
(Bouchard, 2004). Likewise, the Big Three are heritable: Genetic variance accounts for about
50% of variance in adult population’s positive emotionality, 44% for negative emotionality, 52%
for constraint.
Evidence to support those findings and for the average effect size of genetic variance in
predicting personality attributes was furnished by a recent meta-analysis. (A meta-analysis is a
statistical combination and summary of many studies that have researched the same subject in
one analysis, which provides stronger evidence than the results of any single study.) That meta-
analysis included 62 independent effect sizes, more than 100,000 participants of both genders
and all ages, and it found the average effect size of genetics to be .40, meaning that 40% of
individual differences in personality are due to genetic influences, while 60% are due to
environmental influences (Vitasovic & Bratko, 2015).
Heritability of personality traits appears to be stable over time, or as people age (Loehlin
& Martin, 2001). Specifically, using the Eysenck personality scale and a twin registry of 5400
pairs of twins, researchers found that heritabilities were reasonably stable across age for
psychoticism, extraversion, and neuroticism. The personality trait lie, or social desirability,
showed some influence of genetics and shared environment in all but the elderly age group.
Personality traits do tend to change over time, with psychoticism, extraversion, and neuroticism
decreasing as people get older and lie increasing as people get older (Loehlin & Martin, 2001).
Page 5 of 11 The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
Within a longitudinal sample of twins, psychoticism, extraversion, and lie stopped or reversed
their trends between ages 56 and 62, whereas levels of neuroticism continued to drop (Loehlin &
Martin, 2001). The pattern and extent of personality change over time are themselves heritable,
as evidenced by more similar patterns of personality change in monozygotic relative to dizygotic
twins (McGue, Bacon, & Lykken, 1993). Additionally, the heritability of personality traits
appears consistent across cultures (Yamagata et al., 2006).
Mental ability, closely tied to personality attributes, has a substantial level of genetic
influence, reaching a peak .88 heritability estimate in adulthood (Bouchard, 2004). Further,
social attitudes are also heritable. For example, conservatism and right-wing authoritarianism
each have a heritability estimate of about .55 (Bouchard, 2004). Religiosity seems to be
somewhat heritable, with variance in genetics accounting for 30% to 45% of the trait’s variance
in an adult population (Bouchard, 2004). Even such personality tendencies as nostalgia and self-
enhancement are heritable at estimates of .29 and .37, respectively (Luo, Liu, Cai, Wildschut, &
Sedikides, 2016).
As for the future of research examining the genetic basis of particular personality traits,
burgeoning technology and methodology will lead the way. Data from molecular genetics and
brain physiology will likely contribute to understanding the genetic basis of personality traits
(Bouchard & Loehlin, 2001). So far, a few specific genes have been tied to a few specific traits.
For example, the type 4 dopamine receptor (DRD4) gene is associated with novelty seeking, or
the desire to pursue new experiences (Cloninger, Adolfsson, & Scrakic, 1996; Ekelund,
Lichtermann, Jaevelin & Peltonen, 1998). The theory is that people with one form of this gene
are deficient in dopamine and therefore seek out thrills to increase dopamine release. Another
gene, the serotonin transporter gene 5-HTTLPR, which regulates serotonin, is associated with
Page 6 of 11The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
neuroticism (Jang et al., 2001; Munafo et al., 2009). Although these effects are small, they do
provide information on the genetic bases of particular traits.
In summary, heritability is the proportion of phenotypic variance in an attribute in a
population due to genetic variance in that population, and personality traits are heritable.
Although most research in this domain has been done using the Big Five personality scale,
personality traits as defined by different models seem to be heritable. Specifically, they tend to
be heritable in the 40-50% range. Behavioral genetics research—twin, adoption, and family
studies—furnishes the empirical evidence necessary to decipher the relative contributions of
genes and environment to personality traits. There is evidence that personality change across age
is heritable and that the heritability of traits is consistent across different cultures. Modern
technological and methodological advances may allow future research to further delineate which
genes predict which personality traits.
Related Articles
Wbepid0047
Wbepid0052
Wbepid0253
Wbepid0027
Wbepid0166
Wbepid0044
Wbepid0168
Page 7 of 11 The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
References
Bouchard, T. J. (2004). Genetic Influence on Human Psychological Traits: A Survey.
Current Directions in Psychological Science, 13, 148-151.
Bouchard, T. J., & Loehlin, J. C. (2001). Genes, evolution, and personality. Behavior Genetics,
31, 243-273.
Buss, A. H., & Plomin, R. (2014). Temperament (PLE: Emotion): Early developing personality
traits (Vol. 3). Psychology Press: Abingdon, UK.
Cloninger, C. R., Adolfsson, R., & Svrakic, N. M. (1996). Mapping genes for human personality.
Nature Genetics, 12, 3-4.
Ekelund, J., Lichtermann, D., Järvelin, M. R., & Peltonen, L. (1999). Association between
novelty seeking and the type 4 dopamine receptor gene in a large Finnish cohort sample.
American Journal of Psychiatry, 156, 1453-1455.
Jang, K. L., Livesley, W. J., Riemann, R., Vernon, P. A., Hu, S., Angleitner, A., ... & Hamer, D.
H. (2001). Covariance structure of neuroticism and agreeableness: A twin and molecular genetic
analysis of the role of the serotonin transporter gene. Journal of Personality and Social
Psychology, 81, 295=304.
Page 8 of 11The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
Loehlin, J. C., & Martin, N. G. (2001). Age changes in personality traits and their heritabilities
during the adult years: Evidence from Australian twin registry samples. Personality and
Individual Differences, 30, 1147-1160.
Luo, Y. L., Liu, Y., Cai, H., Wildschut, T., & Sedikides, C. (2016). Nostalgia and Self-
Enhancement: Phenotypic and Genetic Approaches. Social Psychological and Personality
Science, 7, 857-866.
McGue, M., Bacon, S., & Lykken, D. T. (1993). Personality stability and change in early
adulthood: A behavioral genetic analysis. Developmental Psychology, 29, 96-109.
Munafò, M. R., Freimer, N. B., Ng, W., Ophoff, R., Veijola, J., Miettunen, J., ... & Flint, J.
(2009). 5‐HTTLPR genotype and anxiety‐related personality traits: A meta‐analysis and new
data. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 150, 271-281.
Vukasović, T., & Bratko, D. (2015). Heritability of personality: A meta-analysis of behavior
genetic studies. Psychological Bulletin, 141, 769-785.
Weiss, A., Bates, T. C., & Luciano, M. (2008). Happiness is a personal(ity) thing: The genetics
of personality and well-being in a representative sample. Psychological Science, 19, 205-210.
Page 9 of 11 The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
Yamagata, S., Suzuki, A., Ando, J., Ono, Y., Kijima, N., Yoshimura, K., ... & Livesley, W. J.
(2006). Is the genetic structure of human personality universal? A cross-cultural twin study from
North America, Europe, and Asia. Journal of Personality and Social Psychology, 90, 987-998.
Further Readings
Bouchard, T. J. (2004). Genetic Influence on Human Psychological Traits: A Survey.
Current Directions in Psychological Science, 13, 148-151.
Plomin, R., DeFries, J. C., Knopik, V. S., & Neiderheiser, J. (2013). Behavioral genetics. New
York, NY: Worth Publishers
Biographies
Heather M. Maranges, M.S., is a doctoral student in Social Psychology at Florida State
University. She studies cognitive resources, social cognition, and their intersection,
complementing traditional social and individual difference methods with those of cognitive
psychology, neuroscience, and genetics. To sample her work, see Maranges & McNulty (2017)
and Baumeister, Maranges, & Vohs (2017).
Tania Reynolds, M.S., is a Social Psychology doctoral student at Florida State University,
studying social competition from an evolutionary perspective. She examined the evolutionary
function of human grief (Reynolds, Winegard, Baumeister, & Maner, 2015) and men’s anti-gay
bias (Winegard, Reynolds, Baumeister, & Plan, 2016). She received the NSF graduate fellowship
to study the hormonal underpinnings of women’s relationship insecurities (Reynolds,
Makhanova, McNulty, Eckel, Nikonova, & Maner, under review). She explores how women
Page 10 of 11The Wiley-Blackwell Encyclopedia of Personality and Individual Differences

For Review Only
compete for mates by strategically disseminating social information (Reynolds, Baumeister, &
Maner, under review) and how women maintain romantic relationships through dieting
(Reynolds & Meltzer, 2017).
Page 11 of 11 The Wiley-Blackwell Encyclopedia of Personality and Individual Differences