[mylovely16]

I am dating my sister's boyfriend's brother and everyone is telling me that if they were to get married, my boyfriend and I would be related. But I'm almost positive that's not true?

[smoothy]

He would be your brother-in-law.

[Wondergirl]

There's no blood relation, so it's not illegal and won't cause weird children. Wikipedia says, "A brother-in-law (plural brothers-in-law) is the brother of one's spouse, the husband of one's sister, or the husband of one's spouse's sister." In the Bible (Old Testament), if a woman was widowed, her husband's unmarried brother was to marry her in order to keep her in the family and for protection.

[Devorameira]

Wondergirl is absolutely right. There is no blood relationship at all, so you don't need to worry about being involved with a "brother-in-law's" brother. There's nothing illegal or immoral about it.