Having a hard time finding “Mr. Right”? According to a study at the University of Newcastle in the United Kingdom, birth control pills could be blocking your game. Major histocompatibility complex (MHC) are genes that determine whether you and your beau are a match. Usually, people are attracted to mates with different MHC smells. However, women on the pill tend to be drawn to men with similar MHC smells—the pills’ hormones alters ones perception.

Clearly, many factors cause a woman to fall for a man—income, sense of humor and good looks—but body odor can definitely seal the deal. Underneath a man’s preferred fragrance his body sends out aromatic molecules that indicate genetic compatibility.

“Not only could MHC-similarity in couples lead to fertility problems, but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odor plays a significant role in maintaining attraction to partners,” says the study’s lead researcher Steward Craig, an evolutionary psychologist at the University of Newcastle in England.