When it comes to the nature vs nurture debate, which camp do you sit in? Well, you're both right because it’s a draw. The study, published in Nature Genetics, reviewed almost every twin study done in the last 50 years and found that 49% of the average variation for human traits and diseases were down to genetics, and the other 51% were due to environmental factors.
"When visiting the nature versus nurture debate, there is overwhelming evidence that both genetic and environmental factors can influence traits and diseases," said lead researcher Dr. Beben Benyamin, from the Queensland Brain Institute (QBI), in a statement. "The findings show that we need to look at ourselves outside of a view of nature versus nurture, and instead look at it as nature and nurture."
Working with researchers at VU University of Amsterdam, Benyamin and his team studied 2,748 classical twin studies—involving 14.5 million pairs of twins—published between 1958 and 2012. These twin studies compared identical twins, which have the same genetic makeup, to non-identical twins, who only share half of their genes. The study looked at a variety of traits—17,804 to be precise—including depression and tobacco use. Traits that were linked with non-identical twins are thought to have more influence from the environment, and vice versa.
While on average genetics and the environment contributed equally to traits, the study found wide variations in individual traits. When researchers looked at the risk for bipolar disorder, for example, 70% was due to genetics and the other 30% was down to environmental factors. However, the risk for developing eating disorders was found to be 60% environmental and 40% genetic.
Benyamin suggests the study has “important implications” for treating diseases. He tells The Guardian that while mental disorders and skeletal traits had a greater genetic influence, environmental factors played a larger role for social values. Genetic factors did, however, have an influence—though at times small—in all traits.