On cross-species hybridisation:

"It's impossible, Lois could never have Superman's baby. Do you think her fallopian tubes could handle the sperm? I gurantee you he blows a load like a shotgun right through her back. What about her womb? Do you think it's strong enough to carry her child? ... He's an alien, for Christ's sake. His Kyrptonian biological makeup is enhanced by earth's yellow sun. If Lois gets a tan the kid could kick right through her stomach. Only someone like Wonder Woman has a strong enough uterus to carry his kid. The only way he could bang regular chicks is with a kryptonite condom. That would kill him!"