To the original question.....of course it's OK if some people don't want kids. In fact, I like that less people aren't having kids just to have them because they think that's what they're 'supposed' to do.
Wouldn't this come down to basic understanding of Responsibility? If you know you can't be responsible for the child, why not abstain, from the act of Reproduction? (I could say it in dirtier terms, but I don't want to Frighten the children...
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I believe, there are no such things as accidents. We all know how Reproduction works, right. It's also why I consider, Males whom Rape Females, as evil and sinister. That's the dark side of Nature.
I want to say, I have no problem, nor do I don't care at all, whether someone decides to have a child or not. I'd be infringing on your Natural Human Rights, if I were to give a shit, but that's how I feel.
I am just presenting reasons, from what I have been reading and understand, for why people are deciding not to have kids. And one area I would suggest to look into is when the concept of using Gold, as the payout for services, started. When the concept of paying for services and goods, shifted from paying with Services and goods, Bartering, (I'll give you 5 Pumpkins, for that Buffalo Fur). I mention this because, It seems all this discussion and the reasons why people don't want kids, is they can't afford the responsibility. Why is it, in todays society, we can't afford the responsibility it takes to provide basic necessities for a child?