As you know my brain is hard-wired for baseline, worst-case kind of thinking, it has to be for the line of work I'm in. So at the very least there's a worst case reason, but it's no guarantee even under the best circumstance.
Well, I think there's a lot to be said for adoption. But I understand the desire to leave something of oneself behind (genetically). I don't know if it's the right reason, but it certainly seems to be a fairly natural one.