Here for the right genes

The Bachelorette

With the final rose being given out next week, there’s one big question on everyone’s mind: Who will Rachel Lindsay choose in the final episode of The Bachelorette? While the consensus at Helix is that Peter is the better choice, we wondered if there was any way we could use a more scientific approach to determine the winner. Does genetics tell us anything about who Rachel might end up with?

While we aren’t going to talk about snake DNA or how/if front tooth gaps are genetic, we are going to talk about the genetics of attraction!

You may have heard the phrase opposites attract. While there are many ways to define opposites, geneticists look to genetic diversity to determine how similar you are to a person. Genetic diversity just means how many differences exist between your DNA and someone else’s. We know that people are 99.9% identical, but their unique differences are what define genetic diversity. More differences = more diverse.

The first study to try to answer whether genetic diversity plays a role in attraction is referred to as the t-shirt study. Back in the late 1990’s, researchers asked a bunch of men to wear a t-shirt for two days in a row. Then, they asked women to rate the smell of each of the t-shirts that had been worn. They found that women preferred the smell of more genetically diverse men suggesting that they were more attracted to these men.

The t-shirt study looked at the major histocompatibility, or MHC, region of the genome to determine genetic diversity. MHC is an important part of your DNA— it is responsible for the regulation of the immune system which allows us to fight off infectious diseases (among other things). The more diversity in your MHC region, the more infectious diseases you might be able to fight off. So, by mating with someone who has a very diverse MHC region, you may guarantee that your children have the best possible chance of fighting off whatever diseases they might come in contact with.

Before you go scouting for MHC-diversity, keep in mind that only 50 women participated in the t-shirt study, and not every woman found dissimilar men’s smells more attractive. The results of the study may have been significant, but it was still unclear how reproducible those effects were. Luckily, other researchers attempted to replicate these findings.

One study from 2003 showed that men preferred MHC-dissimilar women but there was no effect when women were rating men. Still another study from 2005 showed the exact opposite — women preferred MHC-dissimilar men but there was no effect when men were rating women. Still another from 2008 found no significant findings at all. Taking all the research as a whole, there isn’t any good evidence that genetic diversity of the MHC region is correlated with attraction. Although, with all the t-shirts lying around the mansion, Chris Harrison could probably do his own study.

To add to the confusion, there is also evidence that people tend to end up with people who are more similar to them. We call this “assortative mating” and it basically means that, on average, tall people end up with tall people, more educated people end up with more educated people, even that people with similar blood pressure end up together. If we use this principle, then gap toothed people should end up together! Sorry Eric.

Since replication studies of the initial t-shirt study findings have shown mixed results, and there is good evidence of “like attracts like,” it’s clearly too soon to start pairing off based on your DNA. However, we can’t discount the fact that future studies, with bigger sample sizes and improved methods, may uncover a connection.

Until then, it’s probably better to trust statistics. Getting the first impression rose and “quality time” are probably still the best indicators of a connection on reality TV. By our measures, that puts Bryan in the lead. Ugh.

To learn what your genes might actually be able to tell you, visit

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