Clipmark

Meadow vole? Based on new research, musician John Mayer seems like a likely host for two copies of the 334 allele.

Like meadow voles, some men just don't seem to be built for monogamy, whereas others, like swans, mate for life. New research hints that some of the difference might be due to a single genetic variation.

The gene in question, AVPR1a, governs a receptor that regulates the brain's production of vasopressin, a hormone that contributes to attachment behavior with mates and offspring. A few years ago, scientists found that when they added extra copies of the AVPR1a gene to the brains of promiscuous meadow voles, the animals began acting more like monogamous prairie voles, spending more time with partners and grooming offspring. A similar role for the AVPR1a gene has been observed in chimps and bonobos.

Why Men Cheat