Now that more people can’t have kids naturally so IVF more common, we are going to see A LOT more twins 

What are the downstream effects of this demographic shift? Will kids be considered weird if they *don’t* have a twin??

3 is also a powerful number. I can't say for sure how it'll change if we experience hyperindividualization due to personal tech.

otoh, that would be awfully convenient for any couple hard-capping the family they desire ahead of time. would be significantly less vocational uncertainty, assuming no subsistent poverty.