Actually, it’s probably too late for that. The researchers found people who flashed the biggest, toothiest smiles in their yearbook and childhood photos were the most likely to dodge divorce later in life.   How come? Men—but especially women—who grinned in photographs as youngsters tend to have more stable natures and are usually more emotionally upbeat. And both those characteristics improve the likelihood of marriage stability, the study authors explain. Here are four more weird indicators of a lasting union: Neither you nor your wife used to live with another partner. If one of you did, your chances of divorce skyrocket 209%, according to research from Ohio State University. A history of cohabitation hints at a lack of commitment, an ability to end a serious relationship, and knowledge that there are other options out there besides this marriage, the researchers say.  You have sons. Couples with two male children are 17% less likely to divorce than pairs with two daughters, finds a study of 43,000 marriages from Columbia University. Guys are more involved with—and attached to—their marriages if they have sons, the study author explains. (Having one son, as opposed to one daughter, lowers divorce risk roughly 3%.)   You share many of the same Facebook buddies, but those friends don’t all know each other. Un-linked circles of shared “friends”—college frat brothers, family members, work colleagues, hometown pals—are evidence of deep ties and stability in a relationship, says Cornell computer scientist Jon M. Kleinberg, PhD, who examined more than a million Facebook profiles in tandem with researchers from the social network giant.  You both restrict yourselves to just one or two social media networks. Researchers from Oxford University aren’t sure exactly what number equals death for your marriage. But they suggest the more social media sites you both use to communicate—Facebook, Twitter, Vine, Instagram, Snapchat—the less satisfied you’ll feel about your relationship. Maintaining so many social channels may undermine your bond, the study team speculates.  More from Men’s Health: Does Love At First Sight Exist?