An international team of researchers pulled together 50 years' worth of twin studies to find that nature and nurture have about equal influence on human traits, the Huffington Post reports.
"I'd say this settles the debate" between nature and nurture, senior author Danielle Posthuma from Vrije Universiteit Amsterdam tells The Huffington Post in an email.
Posthuma and her team sifted through nearly 2,750 publications from between 1958 and 2012 that examined almost 18,000 traits, comparing how they varied between pairs of identical twins and pairs of fraternal twins, as they report in Nature Genetics this week.
They found that genes and environment both leave their marks. Across all traits, the average heritability that could be chalked up to genetic sources was 49 percent, with the remainder due to environmental factors, or measuring errors, HuffPo says. For about two-thirds of the traits studied, the genetic variance was additive, the researchers note.
In addition, some traits were more heritable than others, the Huffington Post notes. Cleft lip was found to be 98 percent heritable, while risk for bipolar disorder was about 70 percent heritable.