Pleasant, offensive or odourless? Your gene decides

If you find somebody smelly, that’s your problem. Not only literally, but also genetically.

Whether a man standing next to you stinks of urine or smells like vanilla depends on the flick of a gene inside you, say researchers. Scientists at Rockefeller University and Duke University in the US have found that androstenone — an ingredient in male body odour — can smell like either of the two extremes depending on variations in a single gene that expresses an odour receptor called OR7D4.

The findings appeared on Sunday as advanced online publication of the journal Nature.

Androstenone, found in higher concentrations in the urine and sweat of men than of women, is used by some mammals to convey social and sexual information. In men too, the compound — a derivative of testosterone — works as a sex pheromone, though there is no conclusive evidence for it.

In the largest ever study conducted of its kind, researchers led by Leslie Vosshall of Rockefeller presented nearly 400 volunteers with 66 odours at two different concentrations, asking them to rate the pleasantness and intensity of each. It was around the same time that Duke scientists, led by Hiroaki Matsunami, identified OR7D4 as the receptor that androstenone selectively activates.

As the volunteers gave their ratings, the scientists collected their blood samples and analysed the variations in the gene that encodes the OR7D4 receptor. The gene variation affected how each subject thought the androstenone smelt — some found it pleasant, others offensive, while yet others found it odourless.

It has long been suspected that the ability to perceive the odour of androstenone is genetically determined, and this study is the first to confirm so.

“While one may love the smell of coriander, another may find it vile smelling. There have been many theories about the underlying reason for these differences such as culture, experience and memory. Our work demonstrates that a significant fraction of the variability in how people perceive androstenone depends on the genes,” Matsunami told KnowHow.