When I was of reproductive age I made a decision to have two kids for zero population growth and if I wanted more there after, I'd adopt. 4 months after my second, I got snipped to solidify that plan. I don't think I considered, seriously, adopting from the get go, and I'd suggest it is probably a cultural thing, i.e., the culture I was raised in, North East Irish Catholic, presupposed that everyone has kids, usually lots of them. It was like a base principle, so I definitely challenged that idea and departed from it, but only far enough to commit to zpg. I never put a lot of thought into whether or not I'd have kids, just assumed I would.
Having said all of that, I get a lot of personal pride and satisfaction from my kids regardless of their disproportionate consumption of resources compared to a kid born and raised Indonesia, so I completely agree that there is a level of selfishness to parenthood.