I'll just post this without any commentary and let you all go to work :P
http://www.sun-sentinel.com/news/local/southflorida/sfl-1212lovestinks,0,4198179.story?track=rss<snip>
Give these scientists a man and his T-shirt and they can tell whether a particular woman will be more attracted to him -- merely based on a whiff of the T-shirt he wore and the genes in his MHC complex.
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In this latest study, published in Psychological Science, Christine Garver-Apgar, a doctoral student, and Steven Gangestad, Randy Thornhill, Robert Miller and Jon Olp found that the genes did guide behavior. They genetically typed 48 romantic college couples who had been together an average of two years. They asked the women a series of questions about their sexual responsiveness toward their mate -- and their unfaithfulness in the relationship.
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Then they looked at three MHC genes, each with two different varieties, and compared each partner's genetic makeup. The more similar, the less sexually responsive they were to their partners. They also were more unfaithful. The genetically similar women reported more attraction, interest and fantasy toward other men prior to ovulation. When they were not in this phase of the cycle, they showed no sexual interest outside of their partner.
Here is the depressing news: Thornhill believes the partner one chooses is "a compromise. A woman might get a man who doesn't smell so great in MHC genetic sense but he will have other attractive attributes," said Thornhill, a professor at the university. Once the pairing takes place, "love encourages you to do the best you can."
Men do not show an MHC-based sexual preference, the reproductive biologist added.