There are men whose wife had a baby and unknown to him it wasn't his. After the divorce the court rules the kid only knows him as the father and he has to pay child support even though the kid isn't his.
This actually happened to a co worker. He had a paternity test and his baby was not his biological daughter and he divorced his wife. BUT because they were legally married he was financially responsible for the girl.
I'm assuming this was true as the guy was a straight shooter but it wasnt like I ever asked him to verify this.