I was assuming the clone referenced was the one from Vatman, who died shortly after Clark learned of his existence.
I'm sure there are plenty of other possibilities, but just because the clone was alive to father a child doesn't mean he'll still be around when Clark finds out.
As for why Clark would get involved, I think he'd feel some sort of connection/responsibility. The kid would be family. The only other person on the planet with a genetic relation. I can't see Clark not being interested in a child like that.
Paul
The clone I was referring to was the one in Vatman. I was thinking that while in Luthor's possession all types of experiments might have been performed on him before he died. Checking fertility was one. Then one scientist took it further and decided to try to actually conceive a child. No one thinking it possible because of the frog DNA but she fixes that problem. Then things happen that is where Clark as Superman may come into place.
Like Paul mentioned being his only blood relation he feels a duty to this child. Eventually that is.
TLAT
