Sources of human psychological differences: the Minnesota Study of Twins Reared Apart.

  title={Sources of human psychological differences: the Minnesota Study of Twins Reared Apart.},
  author={Thomas J. Jr. Bouchard and David T. Lykken and Matt McGue and Nancy L. Segal and Auke Tellegen},
  volume={250 4978},
Since 1979, a continuing study of monozygotic and dizygotic twins, separated in infancy and reared apart, has subjected more than 100 sets of reared-apart twins or triplets to a week of intensive psychological and physiological assessment. Like the prior, smaller studies of monozygotic twins reared apart, about 70% of the variance in IQ was found to be associated with genetic variation. On multiple measures of personality and temperament, occupational and leisure-time interests, and social… 
Separated twins and the genetics of personality differences: a critique.
  • J. Joseph
  • Psychology
    The American journal of psychology
  • 2001
The evidence from studies of twins reared apart does not support the role of genetic factors in personality and behavioral differences, and an alternative control group consisting of biologically unrelated pairs of strangers matched on all environmental factors common to pairs of separated monozygotic twins is proposed.
Individual differences in adult ego development: sources of influence in twins reared apart.
A behavior genetic analysis of the personality dimension of ego development was carried out on a sample of 45 pairs of monozygotic twins and 28 pairs of same-sex dizygotic twins, indicating that reared-apart twins were similar in trait levels of egoDevelopment and that such similarity could not solely be attributed to measured similarity in cognitive ability, including verbal reasoning.
Heritability of interests: a twin study.
The authors show that heritability can be conservatively estimated from the within-pair correlations of adult monozygotic twins reared together and propose a model in which precursor traits of aptitude and personality guide the development of interests through the mechanisms of gene-environment correlation and interaction.
A genetic and environmental analysis of the California Psychological Inventory using adult twins reared apart and together
The California Psychological Inventory (CPI) was administered to a sample of 71 pairs of monozygotic and 53 pairs of dizygotic twins reared apart (MZA, DZA, adult twins) and 99 pairs of monozygotic
Apart from genetics: What makes monozygotic twins similar?
Author(s): Mandler, George | Abstract: Identical (monozygotic) twins have attracted special attention for the study of behavior genetics. Some of the assumptions and results of these studies are
Twin Studies in Psychiatry and Psychology: Science or Pseudoscience?
It is concluded that there is little reason to believe that twin studies provide evidence in favor of genetic influences on psychiatric disorders and human behavioral differences.
The Complexity of Personality: Advantages of a Genetically Sensitive Multi-Group Design
This study investigated the sensitivity of heritability estimates to the inclusion of sibling pairs, mother–child pairs and grandparent–grandchild pairs from the German Socio-Economic Panel Study in addition to a classical German twin sample consisting of monozygotic- and dizygotic twins.
Same-age unrelated siblings: A unique test of within-family environmental influences on IQ similarity.
Pairs of unrelated siblings of the same age, reared together from infancy (UST-SA), uniquely replicate the rearing situations of dizygotic (DZ) twins. These dyads offer a new behavioral-genetic


Genetic and rearing environmental influences on adult personality: an analysis of adopted twins reared apart.
Analysis of twin intraclass correlations and the results of models fit to the twin data demonstrate that the heritability of most scales and five factors of the CPI is about 50%, and that the retrospectively gathered rearing environment measures generally explain very little variance in adult personality.
Personality similarity in twins reared apart and together.
The overall contribution of a common family-environment component was small and negligible for all but 2 of the 14 personality measures and evidence of significant nonadditive genetic effects, possibly emergenic (epistatic) in nature, was obtained for 3 of the measures.
Genetic and Environmental Influences on Religious Interests, Attitudes, and Values: A Study of Twins Reared Apart and Together
The role of genetic and environmental factors in the expression of religious interests, attitudes, and values was examined using data from adult twins reared apart and adult twins reared together.
The Louisville Twin Study: developmental synchronies in behavior.
The overall results pointed to a strong developmental thrust in the growth of intelligence, which was principally guided by an intrinsic genetic ground plan, and Qualitative features of home and family did not add significantly to prediction of offspring IQ.
Separated fraternal twins: Resemblance for cognitive abilities
The effect of early environment on cognitive ability was assessed by analyzing the association between a degree of separation index and twin resemblance, and some significant effects were found, but these were consistently in a counterintuitive direction.
Frequency of social contact and intrapair resemblance of adult monozygotic cotwins—Or does shared experience influence personality after all?
These data, obtained from a nonselected, population-based cohort of twins, challenge the widespread assumption that experiences shared by siblings make little or no contribution to similarities in their adult personalities.
Genetic influence on life events during the last half of the life span.
Genetic influence on perceptions of major events later in life was assessed with a combination of twin and adoption designs as part of the Swedish Adoption/Twin Study of Aging (SATSA). The SATSA
Habituation of the skin conductance response to strong stimuli: a twin study.
Biometric model testing indicated that stable individual differences in uncorrected SCR amplitude and in habituation slope are primarily determined by non-additive genetic factors.
The diagnosis of zygosity in twins
The methods required for highly accurate zygosity diagnosis using blood typing, fingerprints, and anthropometry are outlined.