There's a reason that the desire to have children is so strong. It's got everything to do with perpetuation of the species, in the long term, and perpetuation of your own DNA -- your dimples, your partner's offbeat sense of humor -- in the short.
Of course, there's a small but satisfied contingent of people who opt not to have kids, and that's their prerogative. But what about those people who can’t get pregnant naturally? Do they owe it to society to quell their yearning for a biological child and turn instead to adoption?