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Biological Compatibility and Sex Lives

Biological Compatibility  involves determining which HLA genes someone carries and how different they are from a potential partner or current partner.  HLA (Human Leukocyte Antigen) are genes involved in immune function. Scientific research has shown that men and women are more sexually attracted to partners with HLA genes dissimilar to their own.

The Sweaty T-Shirt Study

 About 20 years ago, a ground-breaking research study was conducted out of Bern University, Switzerland by Professor Claus Wedekind. Today it is fondly referred to as the “sweaty T-shirt study”.


In the study, men were asked to wear the same T-shirt for two consecutive nights. Without ever having met the men in the study, women were asked to smell the T-shirts and rate the odor from most pleasant to least pleasant. Dr. Wedekind found that three genes, namely the HLA (Human Leukocyte Antigen) genes A, B and DR played an important factor in how women rated the T-shirts.


The results? The more different the DNA sequence of these genes was from their own, the more “pleasant” the odor. The women were attracted to the smell of the man with the most opposing sequence. They also report better sex lives, greater physical attraction and a higher likelihood of a successful long-term relationship. 

Why the Increased Sexual Attraction?

It should be no surprise that those most closely related to us will share more HLA genes in common. That is because like all our genes we inherit from our parents, one copy comes from mom and one from dad. Researchers have observed that if two people with similar HLA’s have a child then the ability of that child’s immune system to recognize a diverse group of pathogens will be diminished. Therefore, if we have a child with someone who has very different HLA genes from ourselves, then the child receives immune genes from both parents that are different. This provides the individual with a strong and diverse immune system.