Ever wondered what is governing your health and the ups and downs associated with it? Is it just genes or mother nature or seasonal changes in environment or is it just the two extra pints of ale that you gulped down last night? Well it seems that researchers decided that the issue be resolved in an old-fashioned way of a duel – Nature vs. Nature.
University of Queensland researcher Dr Beben Benyamin from the Queensland Brain Institute collaborated with researchers at VU University of Amsterdam to look for an answer to this puzzle by reviewing almost every twin study across the world conducted in the last 50 years, involving more than 14.5 million twin pairs.
Turns out that the duel ended in a near-draw with genes losing it out with 49 per cent as compared to environmental factors which went home with 51 per cent. Although genetic and environmental factors have had an equal say in health conditions, the findings of the study published in Nature Genetics reveal that at an individual level the effect of the two factors in question will vary significantly.
Consider the case of say bipolar disorder. The risk of a person of coming down with the disorder is 70 per cent due to genetics and 30 per cent due to environmental factors. In 69 per cent of cases, the study also revealed that individual traits were the product of the cumulative effect of genetic differences.
“When visiting the nature versus nurture debate, there is overwhelming evidence that both genetic and environmental factors can influence traits and diseases,” Dr Benyamin said. “What is comforting is that, on average, about 50 per cent of individual differences are genetic and 50 per cent are environmental.”
Professor Peter Visscher from QBI said the study was performed using publications from the classical twin design, which compares the similarities of identical twins who share all their genes, to those of non-identical twins who share half their genes.
“Twin studies have been the main method for researching the genetic and environmental sources of variation between humans for a long time because of the availability of the two types of twins,” Professor Visscher said.
The study involved a meta-analysis of 17,804 traits from 2748 publications between 1958 and 2012, based on data from 14,558,903 twin pairs. The paper is online here.
100% nurture.
All the evidence points towards experiences and environment being the only factors in both health and behaviour.