I'll contest this post. A cuckoo bird tricks other birds into raising its chicks by laying its eggs in their nest. The parent cuckoo either pushes the other eggs out of the nest, or the baby cuckoo starves them to death and/or pushed them out of the nest because cuckoos actually get really fat and violent. I refuse to use the term "cuck" because I read this stuff out of a nature book at a young age and its just not the same thing. That's just my idiot devotion to semantics though. Cuckoo birds don't literally fuck the other species female as far as I know. Hell, its the damn female that lays the eggs, if anything a woman shitting an offspring on two adoptive parents is the real "cuck" if you want to get literal.
I think this has to do more with people desperately wanting a term to insult their fathers because their Mom cheated on them. Maybe your parents were just shitty. Join the club. We're kind of overcrowded, I know, but maybe we can make room for you.