It's not Just Nature and Nurture: History Influences How Genes are Expressed

It's not just about nature and nurture; it's also about historical context. Scientists have found that the role of genetics in complex traits actually varies over time.

"I liken it to a kind of uncertainty principle or 'observer effect,' for genetics," said Nicholas Christakis, one of the researchers, in a news release. "In principle, any study of how DNA affects bodily outcomes may thus be finding effects that are not ever-enduring, or may be missing effects that-but for the timing of the research-are enduring."

In order to better understand the effects that time might have on genetics, the researchers focused on a specific gene variant in the FTO gene that is widely known to be associated with obesity. They then looked at data from the Framingham Heart Study and found a difference among people with this gene, depending on their era of birth.

So what did they discover? People born before 1942 did not display an association between the risk variant and obesity. People born after 1942, though, showed a stronger association than had been previously reported.

"It suggests that even more caution and humility in modern genetics research is warranted," said Christakis. "It also suggests that if large-scale genetic association studies with this gene had been conducted a generation earlier, they could have had different results."

The findings reveal that time period has a huge role in how genes are expressed. It also shows that examining phenomena such as the rise in obesity becomes a matter of "disentangling" the strands of historical and contemporary environmental factors that interact with genetic features over time.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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