English is my second language and I did not want to sound rude. I meant 'the guy that is supposed to be the biological father and he is not but he doesn't know'

English is my second language and I did not want to sound rude. I meant 'the guy that is supposed to be the biological father and he is not but he doesn't know'. In Spanish, we have a very rude word for these men: 'Los cornudos'. I love the conciseness in languages but I don't like to sound rude in HN. Sorry! ;-)