(Our happy hour fact to amaze your drinking buddies with.)

According to a new study, birth control pills can sway a woman's taste in men toward those who are less genetically compatible.

Scientists have theorized that humans possess a smell-triggered sense that helps determine whether a mate is compatible (compatibility is defined as having genetically differing immune systems). Now British researchers have found that taking the pill causes women to be attracted to the smell of men with a similar cluster of immune system genes.

Not only does this genetic overlap make it slightly less likely a couple could eventually conceive a healthy child, but once a woman is off the pill, she may no longer be as attracted to her partner.

Basically, if your wife or girlfriend is thinking of getting off the pill, prepare for your immune system to stink.