★★★★☆
Bokomtale Blueprint
How much of your personality is determined by genes, and how much is shaped by family, friends and environment? 50 years of cutting edge behavioral genetics research in one easy read.
Plomin pioneered the research into heritability by studying twins and adopted children. This made it possible to factor out the percentage of similarity between parents and children that was due to nature (i.e. DNA) and what percentage that was due to nurture (upbringing and environment).
— “For example, the most important environmental factors, such as our families and schools, account for less than 5 per cent of the differences between us in our mental health or how well we did at school – once we control for the impact of genetics. Genetics accounts for 50 per cent of psychological differences, not just for mental health and school achievement, but for all psychological traits, from personality to mental abilities. I am not aware of a single psychological trait that shows no genetic influence.”
The past 20 years, Plomin has done research into identifying the genes responsible for psychological traits. But this has proved much more difficult than twin studies, since pathways between genes and traits are hard to trace because each tiny DNA-difference has many different effects (so called “pleiotropy”) and each trait is influenced genes (“polygenicity”). So there’s a huge gap between which effects of heritability that may be detected (by using twin and adoptee studies) and what may be explained by genetic sequencing.
Genetic testing and statistical analysis of large populations are promising
— “For the first time in psychology, polygenic scores will make it possible to identify problems on the basis of causes rather than symptoms”
Key takeaways
- Parenting is overrated. Personality and intelligence mostly shaped by genes, not parenting.
- Correlations that seems like being caused by environment, are quite often mediated variables caused by genetic factors.
- Psychological disorders are just the extremes of quantitative dimensions -> ‘Abnormal is normal’.
- “socioeconomic status should be more heritable as a country becomes more meritocratic. As environmentally driven differences decline, genetic differences account for more of the remaining differences in socioeconomic status.”
bookshelves: psychology, science, statistics, e-books, biology