I've got three sisters and they're all younger. I think that that has been a huge influence on who we all are. Both due the experience of growing up with them, as well as the psychology of birth order and such.
it is an influence, but basically every person who learns this bit of trivial seems to have to explain how it explains something about my behavior. Like when i worked as a cashier and the vast majority of my peers were young ladies, and I fit in well. I'll hear about how the two are connected, but no my demeanor when I'm in a work environment is not the same as my demeanor when I'm in my parents home if it was that would be a problem.