Amongst everyone I know who don’t have kids, it’s all either lesbian/gay people, people with infertility, women who wasted their fertile years on men who fobbed them off with being “not ready yet”, or people who didn’t meet the the right person.
Regarding actually ‘choosing’ not to have children it’s not necessarily because they don’t want kids either- I know one woman whose brother had a hereditary condition and chose not to have children because she doesn’t want to go through what her mum went through, and someone else who has a hereditary mental illness that they’d be likely to pass on and would stop them being able to be a reliable parent.
Out of everyone I know without kids, the exception, definitely not the rule, is I do know a couple who decided in their twenties they weren’t going to have kids. I never really understood their rationale when them explained it, above them thinking it would be too much hassle and responsibility, and to my eyes, it seemed they wanted to infinitely extend their adolescence. Up to them really. I hoped at the time they wouldn’t regret it later.