When dating how close is too close?

My cousin's aunt wanted my little brother to date her daughter and my whole family started fake vomiting.
So to be clear this is the cousin of our cousin.
I said that it would be good because they both have no one and they both need to meet someone and we can help them.
My whole family said that I was weird.
So they started asking me would I date the half brother of my cousin as well ( no relation) I said yes and they acted like I was horrible.
Would you date the cousin of your cousin?
How about the unrelated brother or sister of your cousin.
I wouldn't seek it out but its just not that bad to me