You're 37 and single.

You know this, of course, yet there's always that one person in your life — at the dinner table, on the phone or through every other medium imaginable — who feels the need to remind you of your singleness. Over and over again.

Toxic relatives are a big source of stress in our lives. You seem to feel worse with each moment you spend with them, and yet there you are, lending an ear while they take inventory of your shortcomings in agonizing detail.

So why do you put up with it?

From real life to TV, it's a constant drumbeat

A new study from researchers at the University of California, Berkeley, and Bar-Ilan University in Israel sheds light on this phenomenon. Knowing that so many people deal with this dynamic for at least part of their lives, they posed a few questions: Who are those toxic people, and why don't we – as recipients of their toxicity – just cut them off?

What they found was part totally obvious and part highly intriguing. On the one hand, participants more often reported that the most difficult people in their lives were female family members such as wives, mothers and sisters. The stereotype appears to play out. But on the other hand, we also don't want to get rid of them. We kind of need that influence in our lives, as much as we try to avoid it.

What else explains why so many people share this dynamic?

The ties that bind

"The results suggest that difficult people are likely to be found in contexts where people have less freedom to pick and choose their associates," says Dr. Shira Offer of Bar-Ilan University, who co-authored the article with Professor Claude Fischer of UC Berkeley.

The researchers say more people tend to classify the women in their lives as "difficult" because they're often more involved in the family's inner workings than men. "These are people with whom our lives are so complexly intertwined," says Offer in the university news release. "Many are close family whom we need and even love; others we just can't escape."

We don't escape, the researchers say, because they're family. We can't choose them, but they make us better. "Social norms do not allow us to simply walk away from them, however much this might be tempting to do sometimes," Offer said.