You cannot as a parent abrogate your responsibilities to your children because you live in 'a free society'. That means you cannot starve them, work them to exhaustion, beat them needlessly etc. Passive methods of aggression (simply not clothing, feeding and/or evicting a child who cannot fend for themselves) is still aggressing.
Its never an easy answer when it comes down to this because (its coming) people will invariably bring in rape and incest to the equation. If it was completely consensual sex, then sorry, freedom and living in a free society doesn't mean free from responsibility of your actions. Passive forms of aggression (as I said) are still forms of aggression. Don't want to be burdened with your child, give it up for adoption. That doesn't mean you can leave them out for the wolves, toss them into the ocean or any number of methods that ancient man did to not burden themselves with their responsibilities.
In the case of rape and incest, the undeniable fact is that an Embryonic Human still has inalienable rights, the most basic of which is Life. Further, just to quash the incest argument, the chances of serious genetic defect for incest is mostly a myth. That would require multiple generations for that sort of thing to come out.
Let me add one more thing. My belief has nothing whatsoever to do with religion or my religious beliefs. I'm a Deist and I accept Rational Thought, not Revealed Thought. We only get one pass in this life and thats it. I personally think its abominable that we have been a part of a civilization that continues to murder its own people in the name of progress.
Michael Crichton: Why Politicized Science is Dangerous