As amazing as I find it the biological son idea doesn't quite seem right. I'm gonna have to say adopted would make a lot more sense. Besides, can mutants even reproduce? I've been trying to figure that one out for a story I'm writing.
Bological...the little turtle looks so muck like Himeko with his pruple hair....so it should be...though it would be strange seeing as Himeko is a human and Raph is a anthro turtle but ah well, people will get over it XD