Human behaviour shapes our DNA and descendants

10 March 2022

Our choice of partner can have a direct effect on the genomes of our descendants, an Institute for Molecular Bioscience researcher has found in work that has led to a national award.

Dr Loic Yengo has received the Ruth Stephens Gani Medal from the Australian Academy of Science for his research on the genetic causes and consequences of human behaviour.

People seek partners who are like themselves

Dr Yengo discovered thousands of DNA variants that are associated with human traits, and showed that the pattern of those variants in the human genome is, in part, the consequence of people seeking partners who are like themselves.

“I became involved in this research because when studying the genetics of various diseases and human traits, the data was showing some unexpected patterns,” Dr Yengo said.

“One of the classical assumptions in genetic studies is that people look for partners randomly in the population, but this isn’t true, so the data is shaped by human behaviour.”

This realisation led Dr Yengo to dive into the question of how choice of partners influences the genetics of our descendants.

“I’m interested in these questions because our choice of mate shapes the next generation, including the likelihood of children having risk factors for disease,” Dr Yengo said.

Choosing genes for height and intelligence

“This behaviour may also exacerbate social inequalities if people select partners with a similar level of education, which is a strong predictor of future income.

“This research helps us answer some big questions around whether a trait is caused by our environment or our genes.”

“If you only look at whether spouses resemble one another, you cannot tell the underlying mechanisms – do people choose similar partners because they are more likely to have that person in their environment, or is it an active choice?”

The answer, as it turns out, depends on the trait.

“There are genes that predispose people towards being more intelligent and others towards being taller.

We found that a correlation between those genes across spouses, reflects an active choice being made towards height and intelligence.” he said.

Similarity in BMI is driven by environment

“But we find the opposite with obesity in studies from Europe and Japan, where the similarity in BMI between spouses seems to mostly be driven by the environment - they tend to eat similar foods and have a similar lifestyle to one another.

Dr Yengo developed new statistical methods of harnessing big data to answer these questions, which ultimately help him and other researchers understand more about disease prevalence and whether a disease or trait is driven by the environment or our genes.

In some cases, such as same-sex couples, the link between partner choice and biological children is not as clear-cut.

“There is evidence that same-sex couples also choose similar partners, but we can’t look at the data in the same way, because they won’t have biological children that include the DNA of both parents, though of course the choice of who provides genetic material for their children is very unlikely to be random.”

The Ruth Stephens Gani Medal recognises research in human genetics by early-career researchers, and is one of 20 awards being announced today by the Australian Academy of Science.

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