Birth order mainly takes presidence in my opinion in more organized "nuclear" families from single family homes after WWII. In my family, we grew up extended, knowing cousins, half raised by other relatives, our old people dying at home. That's how my youngest sister ended up being an ESFJ 9w8 who feels it's her duty to caretake the family. She's the BABY yet she says things like why don't I get to be weak, when she constantly volunteers to mother her own mother and nag her sisters, and keep the family together. Though my one middle sister is the typical mess of a middle child (actually, not a mess, more of a sociopathic asshole) my other middle sister is an ISFJ who is possibly a 4, who is an artist but used to be a super hard worker, she managed Taco Bell when she was like twenty, always gently unobtrusively giving too much to others, and a natural married mom without much ambition. She could be a 2, but it doesn't explain her artsy streak or teenage leather outfits.