Birth control 'affects sexiness of a man's scent'

Birth control pills may affect how appealing a woman finds a man's scent - potentially steering her toward a mate who is genetically similar to her, according to British researchers.

The sense of smell is thought to be important to mate-seeking animals and humans. Genes of the major histocompatability complex (MHC) play a role in a person's odor, and people tend to be attracted to those with an MHC makeup that is dissimilar to their own.

This could have evolutionary significance, since genetic diversity in a couple increases the chances of having healthy children.