In describing in-laws on urban dictionary, one sentence says, “The wife’s mother came around yesterday. I knew it was her as soon as she knocked on the door. All the mice threw themselves onto the traps.” There are entire sites dedicated to hating on in-laws — in both directions — but what is it exactly, that causes parents to dislike their son-in-law so much? According to one new study, it could simply be that they don’t think their child’s spouse provides enough financial or emotional support.

Researchers found that at its core, a parent’s dislike for their child’s spouse was really based on whether or not they would be able to provide for their child, and to a larger extent, their grandchildren. This was because having a son-in-law who couldn’t provide usually meant that they would have to step in to compensate, according to a statement.

“This additional help by the parents open them up to ‘exploitation’ by the children — a child can afford to settle for a less supportive partner in the knowledge that their parents will pick up the slack,” Dr. Tim Fawcett, a University of Bristol researcher and author of the study, told TODAY. “The result is that children will settle for a less caring partner than their parents would ideally like, hence the conflict over mate choice.”

Interestingly, their study doesn’t rely on surveys of a large group of people, but rather, on a computer-based model and previous studies, which have shown that parents show a stronger preference than their children in the social class, family background, ethnic background, and educational level from where their child’s spouse came from.

The computer model simulated the evolution of parental behavior as their daughter searched for a partner, and showed that parents preferred a son-in-law who is more caring and supportive — “basically any kind of help that increases the reproductive success of their offspring,” Dr. Fawcett told TODAY.

Financial and emotional support are not only impoortant to parents either. Research has found that even though people from of both low and high socioeconomic backgrounds tend to feel the same way about marriage, those from lower backgrounds tend to divorce more. The reason: "Low-income respondents were more likely than affluent couples to report that their romantic relationships were negatively affected by economic and social issues." If a couple divorces, children could be faced with difficulties later in life, including depression, inflammation, bad school grades, and negative behavior.

Future studies would investigate real-life preferences, as well as different aspects of quality, Dr. Fawcett says. He also said it was unclear whether fewer resources among parents could affect their opinions. They also found that the conflict could be stronger when fathers control resources rather than mothers, and when parents have a daughter rather than a son.