Research for the nature versus nurture analysis drew on data from almost every twin study across the world from the past 50 years. Photo by Pressmaster/Shutterstock

BRISBANE, Australia, May 19 (UPI) -- One of the longest debates in history -- nature or nurture -- has turned out to be a draw because they equally influence health, researchers say.

Researchers analyzing 50 years of data collected on 14.5 million pairs of twins found that variation between them for traits and diseases worked out to 49 percent based on genetics and 51 percent environment in most cases.


"When visiting the nature versus nurture debate, there is overwhelming evidence that both genetic and environmental factors can influence traits and diseases," said Dr. Beben Benyamin, of the Queensland Brain Institute, in a press release.

"What is comforting is that, on average, about 50 per cent of individual differences are genetic and 50 per cent are environmental. 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."

The conclusion from studying reports of similarities and differences for nearly 18,000 traits across more than 2,700 studies shows that future research should consider both genetics and environment because of their equivalent average influence on development.

Researchers say genetic and environmental influence was balanced across most traits, though some had wider differences. Bipolar disorder, for example, was found to be about 70 percent genetic and 30 percent environmental. The research also showed individual traits were often the result of the cumulative effect of genetic differences.

The study is published in Nature Genetics.