Then how can you explain no correlation before the daughter has become a teenager? If I understood you correctly, you suggest that parents of daughters divorce more often because the daughter was born to a couple of stressed parents (which is more likely to happen than a boy born to that family). If that would be the only cause of the divorce (I'm oversimplyfying, of course), then there would be no difference whether the daughter is a teenager or not. Perhaps parents think of taking care of a child in their first years of life as a moral obligation, which would reduce the divorce rate. However, it's still suspicious that the divorce occurs around the time the daughter reaches puberty, not some time earlier (after she's 5 or something).