The only way I can see Voldemort having a child is in the "this is the only way to stay immortal"-way. Maybe he would have felt lust earlier, but the way I see Voldemort, he didn't feel much after his "rebirth" in GoF.
I can easily picture Bellatrix agreeing to give birth to Voldemorts child; we can see in the books that she adores/loves him. However, I somehow can't picture them actually sleeping with each other. I'm thinking of some kind of magical in vitro fertilisation.