Just to toss a bit of a hot potato into the discussion...
Male rape victims have to pay child support if a child is conceived. In multiple cases, courts have held that being a victim of statutory rape (I think the father was 12) have to pay up, as do fathers whose sperm was retrieved from a used condom (even if no actual intercourse takes place between the father and mother), and fathers who were incapable of giving consent at the time (such as being blackout drunk).