In the context of current concerns about replication in psychological science, we describe 10 findings from behavioral genetic research that
"In the context of current concerns about replication in psychological science, we describe 10 findings from behavioral genetic research that have robustly replicated. These are ‘big’ findings, both in terms of effect size and potential impact on psychological science..."
All psychological traits show significant and substantial genetic influence.
No traits are 100% heritable.
Heritability is caused by many genes of small effect.
Phenotypic correlations between psychological traits show significant and substantial genetic mediation. ["For example... a multivariate genetic analysis of intelligence, reading, mathematics, and language in over 5,000 pairs of 12-year-old twins showed that genetic factors consistently accounted for more than half of the phenotypic correlations..."]
The heritability of intelligence increases throughout development. [Cognitive scores of young people are subject to more environmental influence, but these influences fade out to negligibility in adulthood.]
Age-to-age stability is mainly due to genetics.
Most measures of the “environment” show significant genetic influence. ["How can measures of the environment show genetic influence? The reason appears to be that such measures do not assess the environment independent of the person. As noted earlier, humans select, modify, and create environments correlated with their genetic behavioral propensities such as personality and psychopathology... For example, in studies of twin children, parenting has been found to reflect genetic differences in children’s characteristics such as personality and psychopathology."]
Most associations between environmental measures and psychological traits are significantly mediated genetically. ["For example, rather than assuming that correlations between parenting and children’s behavior are caused by the environmental effect of parenting on children’s behavior, one should consider the possibility that the correlation is in part due to genetic factors that influence both parenting and children’s behavior. Individual differences in parenting might reflect genetically driven differences in children’s behavior or differences in parenting might be due to genetically driven propensities of parents that are inherited directly by their children."]
Most environmental effects are not shared by children growing up in the same family. [Most environmental effects are not shared environment, but nonshared environment.]
Abnormal is normal. ["Quantitative genetic methods suggest that common disorders are the extremes of the same genetic factors responsible for heritability throughout the distribution..."]
