Fifty Years of Twin Studies
Five discoveries about nature and nurture from a landmark meta-analysis
What makes us who we are? To what extent are the differences between us written in our genes, and how much do we owe to the environment? Philosophers, scientists, and armchair theorists have debated this question for centuries - but a groundbreaking meta-analysis of twin studies offers the clearest answer yet.
Spanning over 50 years of research, 2,748 publications, and more than 14 million twin pairs, the study reveals five striking insights into the nature of nature and nurture - among them, that every trait is partially heritable, that the influence of genes often fades with age, and that the home you grow up in has surprisingly little effect on how you turn out in life.
In this post, I’ll break down the findings that challenge everything we thought we knew about how genes and environment shape us.