Dear Prudence: My mom asked me to accompany her to a distant relative's 60th birthday celebration. She has a big family and we never really interacted much with her side, so I thought I'd go to meet some of my relatives. While I was eating dinner I looked up and saw my boyfriend's mother. I was surprised to see her and went over to say hi. Suddenly, my mom came over and began chatting with her, introducing me as her daughter.

It turns out that my mother and my boyfriend's mother are actually first cousins. My boyfriend and I had been dating for a year and we were starting to talk about our future together. I don't know what the laws are, but even if it's legal for us to marry, I feel creeped out by the idea of my mother-in-law also being my second cousin.

My boyfriend is devastated and says it doesn't matter.

I feel heartbroken with the idea of breaking up but I feel like it's not right. Would it be completely gross if we stayed together?

Prudence says: I think it would be ridiculous for you not to stay together.

My understanding is that the laws on cousin marriage are only about first cousins; I think they should be repealed because this is not the state's business.

There's nothing to be devastated or creeped out about -- the whole thing is actually kind of funny. If you and your boyfriend eventually decide to marry, you can get genetic counseling before you have children, which will likely be reassuring to you both.

But no one should do more than shrug about kissing-second-cousins.

Send questions to prudence@slate.com