@Crow
How are they not cousins? They will still carry their father’s name and your children will carry your name? Or, will you erase their father’s name and give them yours? Civilised people moved on from these barbaric cultural practices and we still shag the wives of our brothers. .
It actually isn't that common anymore.
Somalis even used to practise the opposite. The sister would marry her dead sisters husband in order to raise the kids with him.