I am not saying people raised this way don't help their siblings/niblings monetarily. I just mean they aren't obliged to consistently do so. E.g., my sibs and I routinely got birthday money from our grandparents, but not from our uncle or aunt, who had big families of their own to see to. They were kind and hospitable and so on, and if any of us had been in a real jam where they could have helped I am sure they would have been happy to, but they weren't the ones stepping up over and over to pay for music lessons or something. They were also not expected to leave us any money, nor were my parents expected to leave anything to their niblings. My parents' childless aunts/uncles often did, but were seen as having the choice whether to be that sort of relative or not.