Sir Richard Branson wakes up every day at 5am and thinks you should too. PepsiCo CEO Indra Nooyi goes even further setting her alarm for four. Twitter CEO Jack Dorsey is up at 5:30am for a jog. They're not outliers. One informal survey found that a full 90 percent of executives are early risers.

Read enough of these stories -- as well as the avalanche of posts and articles out there urging you to up your productivity by getting up early -- and you're bound to feel a little guilty if you're not naturally up and at 'em at dawn. But before you start beating yourself up for your lack of discipline, you might want to check out a new study from 23andMe.

You're not just lazy.

As a genetic testing company, 23andMe has amassed a treasure trove of information on customers' genes. Recently a team of its researchers combed through this data, searching the the genomes of 89,283 people for correlations between particular genes and a person's self-reported status as a lark or night owl. They found 15.

That means that there is probably a biological basis for people's preferences for early mornings or late nights, but that the genetics behind our inclinations is complicated. Each of the 15 regions of the genome identified by the study "might shift your chances of being a morning person by between 5 and 25 percent," study co-author David Hinds told The Verge.

Even though there's no single 'morning person gene' the results indicate that your love of the snooze button isn't entirely down to laziness, personal choice or your environment. Your body is probably pushing you towards being being a night owl. "We think of our preferences as things that we come up with--things that are kind of spontaneous parts of who we are--but they do have a basis in biology. I think it's just very interesting for people to see how their biology influences who they are," says Hinds.

Still, the boosters of early morning might have a point.

The results might give a boost to the legions of people who struggle to follow the advice of the likes of Branson (a hefty 56 percent of those 23andMe queried called themselves night owls). However, the study also turned up some associations that bolster the case that, if you can manage to make yourself get up early, you probably should.

"Early risers were significantly less likely to have insomnia or need more than eight hours of sleep per night. They were also less prone to depression," reports the UK's Guardian newspaper in its writeup of the study. "The researchers also found that after taking into account the effect of age and sex, morning people were likely to have lower--and thus generally more healthy--BMI, or body-mass index, a measure of the ratio between height and weight."

The article cautions that, "none of these correlations... necessarily implied a cause-and-effect relationship." Still, knowing that night owls are more likely to be fat, depressed, and suffer from insomnia sounds like a pretty good reason to set that alarm a bit earlier if your body is willing to comply.