Genes and environment balance each other

Human traits depend on both nature and nurture

Twins

MATCHED PAIR  Studies of more than 14 million sets of twins indicate that human traits, on average, are dictated equally by genes and environment.

Photobank.ch/Shutterstock

Combatants in the age-old battle of nature versus nurture may finally be able to lay down their arms. On average, both nature and nurture contribute roughly equally to determining human traits.

Researchers compiled data from half a century’s worth of studies on more than 14 million pairs of twins. The researchers measured heritability — the amount of variation in a characteristic that can be attributed to genes — for a wide variety of human traits including blood pressure, the structure of the eyeball and mental or behavioral disorders.

All traits are heritable to some degree, the researchers report May 18 in Nature Genetics. Traits overall had an average heritability of 49 percent, meaning it’s a draw between genes and environment. Individual traits can be more strongly influenced by one or the other.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.