- Married couples often share physical characteristics which may be a result of cultural, environmental, or genetic factors
- Queensland Brain Institute’s high-performance computing infrastructure helps analyze genetic data for nearly 50,000 people
- Results show that genetic heritage may influence choice of life partner
Have you ever seen a cheery retired couple speed-walking in coordinated jogging suits and marveled at how much they looked alike? The long years together seem to have fused them into a matched set, nearly identical in height, weight, disposition, and fashion sense.
New research suggests that genetics, more than decades of cohabitation, may be responsible for the similarities. (Well, except for the jogging suits — even science can’t explain those.)
In an attempt to discover if mating preferences are influenced by our genome, Matthew Robinson, of the Institute for Molecular Bioscience at the University of Queensland, Australia, studied more than 24,000 opposite-sex married couples of European ancestry, looking at genetic markers for traits such as height and body mass index (BMI).
“It’s been known for some time that couples often share certain characteristics such as height, education level, religion, political views, and even risk of psychiatric disease,” says Robinson.
The question is why.
Nature, nurture, or genetic destiny?
Several environmental factors may cause couples to resemble one another: Those from similar backgrounds share comparable upbringings and diets, people from the same geographic area may both exhibit that region’s dominant physical attributes, and a shared life (such as experiencing the same hardships, income, healthcare, etc.) can be reflected in physical appearance.
But it’s also possible that people directly choose their mates based on visible, physical characteristics. Robinson's team theorized that if a characteristic has a genetic component (and is therefore somewhat heritable), then couples will be more likely to share the genetic variants associated with that characteristic.
“We set out to investigate whether couples share regions of the genome that underlie a range of different characteristics,” says Robinson. “This tests whether mate choice is shaped by accidents of the environment, culture, or by actual preferences for genetically-based traits.”
Drawing upon a wealth of DNA information about height, BMI, and other traits from large genetic databases, Robinson and his team created a genetic predictor for the husbands in the study and tested to see whether this predictor showed an association with the height, BMI, education, and blood pressure of their wives.
“If there is an association between the predicted height of an individual and the observed height of their partner then that implies that there is a correlation at the genetic regions underlying height,” says Robinson.
Because this method is unbiased by environmental factors, researchers can start to tease apart whether mate choice is shaped by accidents of the environment, culture, or by actual preferences for genetically-based traits (known as assortative mating).
Crunching the numbers
With help from the Queensland Brain Institute’s high-performance computing and storage systems for genomics research, Robinson’s study analyzed 1.2 million genetic markers from 48,000 people.
Robinson’s team also relied upon HPC to conduct a large simulation study that generated fake data very similar to the actual data, so they could test the accuracy of their theory and whether their analyses would give reliable results.
The institute’s computing infrastructure is comprised of 480 cores, with 2TB of shared memory, 200TB of solid state assisted disk storage and a 10GbE + Infiniband connected cluster network. A combination of public domain, commercial, and in-house software was used in the processing and analysis of data.
The fairest of them all
Ultimately, the scientists found a strong statistical correlation between an individual’s genetic markers for height and the actual height of their partner. They also found a significant, but weaker, correlation between markers for BMI and actual BMI, suggesting that people actively chose partners with similar genes to their own.
“The choice of mate based on genetic characteristics influences the way in which many characteristics from height and BMI to disease risk are inherited,” says Robinson.
This may also include other genetically-correlated traits such as disease susceptibility or desire for educational attainment.
The study only examines people of European ancestry currently living in the US and Europe. Its results may not be valid for other populations, particularly those with more diverse genetic heritages or different customs for choosing a mate, Robinson concedes.
However, future uses of the approach developed for this study may improve the accuracy of genetic predictors and lead to better disease screening and treatment.
So remember, when you’re sizing up a potential partner, your genes may be at work in the selection process, nudging you to choose someone tall or short, fat or thin.
Don’t be surprised if the person who winds up speed-walking beside you through the golden years looks a lot like you.