Also, your aversion to cilantro.

By Julia Malacoff
June 20, 2018
Photo: Mind and I / Shutterstock

Not a morning person? Well, you might be able to blame it on your genes-at least partially.

If you've taken a 23andMe Health + Ancestry genetics test, you may have noticed some new traits pop up in your report last week. That's because the genetic testing company just introduced new trait features, including predicted wake-up time, hair thickness, cilantro aversion, and misophonia (the hatred of hearing other people chewing).

In the case of hair thickness, cilantro aversion, and misophonia, the new reports state your likelihood of having these characteristic traits, but as far as wake-up time, the report tells you approximately what your natural wake up time may be. (BTW, here's what happened when five Shape editors took 23andMe DNA tests.)

"Like with most traits, your wake-up time depends not only on your genetics, but also on your environment and lifestyle, so this report tells you about the genetic part of the equation," explains James Ashenhurst, Ph.D., a product scientist at 23andMe. That means the wake-up time in your report is meant to be approximate, not exact-and your lifestyle might dictate a different wake-up time if you, say, work the night shift.

How did they even figure that out? It's actually pretty cool: "We started off by doing a kind of research study called a genome-wide association study that looks for places in our DNA (genetic markers) where research participants who have told us they are morning people tend to have differences in their DNA (genetic variants) compared to research participants who have told us they are night people," says Ashenhurst. Through this process, they found hundreds of genetic markers associated with being a morning person or night person. "Exactly how differences in each of these markers might affect being a morning person is unknown, but previously published studies have suggested that some of them are in or near genes that help regulate circadian rhythms in the brain," notes Ashenhurst. Makes sense, right? (Fun fact: Circadian rhythms are also the reason you can cure your jet lag with food.)

On its own, each marker only has a small effect on a person's chances of being a morning or night person. So, for each customer, 23andMe adds up the effects of their DNA variants at these hundreds of sleep-related markers to predict not just whether they're a morning or night person, but how much of a morning or night person. Based on that analysis, a wake-up time is predicted.


Some of the other new traits, like cilantro aversion, are a little more straightforward. (In case you haven't noticed, there are two camps when it comes to the herb: People who enjoy cilantro, and people who think it tastes like you grated a bar of soap over your food.) "For the cilantro report, the 23andMe research team discovered two places in our DNA (genetic markers) where, on average, people who dislike the flavor of cilantro tend to have different DNA letters (genetic variants) than people who like the flavor," notes Becca Krock, Ph.D., also a product scientist at 23andMe.

By knowing which genetic variants a person has in those two places, 23andMe can predict whether they're more likely to dislike cilantro. It's important to note that, like the wake-up time trait, this also isn't an exact prediction. "That doesn't mean they definitely do or don't like cilantro, because there are other factors besides these two genetic markers at play, like their experiences and environment, as well as other genetic factors that scientists probably don't yet know about. But it does tell you about some of the genetic influences behind the trait," says Krock.

So what's the point of these new features? Well, first and foremost, they're meant to be fun. "The goal of these reports is to look under the hood of your biology to show you how your genetic makeup may influence these traits," explains Krock. "Knowing that genetics is just one factor at play, these reports are meant as a fun way to provide some explanation for how you ended up the way you did." Of course, in the case of these traits, your lifestyle definitely has the potential to trump your genetic tendencies, so it's very possible that what's listed in your report might not match up with reality. (Like all these trainers who've taught themselves to be morning people.)

But there may also be a bigger takeaway for some: "We'd love it if the wake-up time report could spark some reflection about your natural sleep rhythms, which could help you make choices about when to sleep to get more and better-quality sleep," says Krock. We probably don't need to remind you about the benefits of getting high-quality sleep, but if you're wondering how to actually achieve it, find out the actual definition of a "good night's sleep" and how to eat for better sleep.

And, you know, now you can sleep 'til noon, and blame it on your DNA.