Can’t stop hitting the snooze button? Blame biology. Researchers at the genetics company 23andMe say they’ve identified 15 parts of the human genome that influence whether someone is predisposed to be a morning person or a night owl. The study, published in the journal Nature Communications, analyzed sleep patterns of 90,000 individuals and follows similar studies conducted on fruit flies and mice. Though the researchers admit their analysis is far from complete, they say the results will help guide further studies into the understanding of our circadian rhythms.