Is a ‘selfish gene’ making a Utah family have twice as many boys as girls?
Is a ‘selfish gene’ making a Utah family have twice as many boys as girls?
Tags: Population genetics/dynamics, Selfish genetic elements, Sex distorterEwen Callaway, Nature, 2026.
By sifting through an anonymized genealogy database, researchers have discovered a Utah family that has been having twice as many boys as girls for seven generations. It is the first clear evidence that humans might have ‘selfish genes’ that distort the sex ratio of offspring from roughly 50:50, the researchers argue in a preprint posted on bioRxiv earlier this month. The findings have not been peer-reviewed. Such sex ‘distorters’ have been discovered — and studied in great depth — in laboratory animals such as mice and flies, in which their effects can be detected through selective breeding. “If you look, more often than not, you find them,” says Nitin Phadnis, an evolutionary geneticist at the University of Utah in Salt Lake City, who co-led the study.
Theoretical predictions suggest that sex distorters probably do exist in people as well, and that they could produce excesses of biological boys or girls at birth. But humans’ long generation times and low birth rates as well as ethical issues have made such genes — and other ‘selfish’ genetic elements , meaning that they bias their own transmission to future generations whether or not they improve an individual’s biological fitness — difficult to spot.
