If you assumed the only effect in-laws could have on your marriage would be to put it on a path toward divorce, well, you'd be half right. In 1986, a researcher asked 373 newly married couples to rate how close they were to their in-laws. The good news: Husbands who had good relationships with the in-laws had a 20% lower chance of getting divorced over time. The bad: Wives who initially reported being tight with their in-laws had a 20% greater chance of ending up divorced, reports the Wall Street Journal. Terri Orbuch posits that in the former case, "these ties connect the husband to the wife."
But in the case of the initially chummy wife-and-in-laws, the closeness can translate into a lack of boundaries, which over time can make a tight-knit relationship feel like a meddlesome one. The woman may ultimately "interpret what their in-laws say and do as interference into their identity as a spouse and parent," says Orbuch, who notes that men don't take their in-laws' actions so personally. Her advice: The parents of a son should refrain from dishing out the advice, even if they feel close enough to do so; wives should learn how to say "thanks, but no thanks." On the flip side, the parents of a daughter should make an effort to be welcoming, while husbands should be aware that caring for them is interpreted, by your wife, as caring for her. (Read more marriage stories.)