CHICAGO - When it comes to a man’s body odor, the fragrance — or stench — is in the nose of the beholder, according to U.S. researchers who suggest a single gene may determine how people perceive body odor.

helps explain why the same sweaty man can smell like vanilla to some, like urine to others and for about a third of adults, have no smell at all.

Androstenone is in the sweat of men and women, but it is more highly concentrated in men. How one perceives its smell appears to have a lot to do with variations in one odor receptor gene called OR7D4.

They took blood samples and sequenced the DNA of 400 people who participated in a smell perception test done in Leslie Vosshall’s lab at Rockefeller.

What they found is slight genetic variations determine whether androstenone has a pungent smell, a sweet, vanilla-like smell or no smell at all.

The role of androstenone is not well understood in humans, but in pigs it sends a powerful sex signal that puts sows in the mood for love.