Or because it's true. Neither gender is entitled to risk-free sex.
Well, maybe not "risk-free," but I see no reason why the government should enforce a system which causes more risk to one gender than the other when a remedy would be easy to implement.
But maybe, then, you can steer me in the direction of a general legal principle? What is the right that you argue that is being infringed upon here?
It's discrimination on the basis of sex. Women are able to avoid the legal, personal, and financial obligations of parenthood, while men are not.
I know it's tempting to respond by saying, "it's biology," but if you really want to argue that point, the current system of child support is
already a government attempt to protect women from a biological inequality. It's silly now to turn around and say that the government has no right to adjust its remedy a bit in the opposite direction in the interests of preserving equal protection.
There are any number of imaginable legal remedies for the problem. Perhaps women should be given a cash remedy by the state to compenstate the risks they take in pursuit of a common good. Perhaps the task of raising children, which disproportionately falls to women, should become a paid public office in recognition of same.
The government is not, and shouldn't be, in the business of rewarding, punishing, or subsidizing personal choices.
But I find it strange that you rely on 'unavoidable facts of biology' here and deny that any remedy can be provided, but you insist that biology is irrelevant to question of reproductive decisions despite the very different roles men and women play, and that remedy must be provided.
I don't say that it's irrelevant, I just say that the law is not powerless to address that particular inequality.
you have no right to dictate how a 'gift' of genetic material is to be used
Why not? You can, as a matter of contract, specify how
other gifts you give are to be used. If you insist on looking at it in that context, I would argue that expressing your desire not to have children, and/or using birth control, constitutes a verbal or implied contract that the "gift" is not to be used in that fashion.
ETA: Likewise, if the woman dishonestly indicates that she doesn't want kids either, or lies about using birth control, that would constitute an act of bad faith and any resulting "contractual obligations" would be null and void.
Of course, it's pretty silly to look at it in terms of semen being a "gift," in my opinion. For starters, simply giving someone a gift doesn't impose any obligations on you, so, from that point of view, child support shouldn't exist at all. I don't think that's what you intend to argue.