How about this one (true story, small town):

Male X, dates, gets engaged to and gets Cousin A preggers. Goes out one night and decides that Cousin B is more to his taste.

Marries Cousin B and has a baby. Divorces Cousin B and starts dating Cousin C (side note Cousin B starts dating Cousin C’s ex and has a baby with him).

Cousin C and Male X break up and Male X starts dating Cousin A again.

These are first cousins. Needless to say a family reunion is out of the question. When these babies grow up they’re going to be like “brother, cousin? Which is it?”