Every once and awhile I get to thinking about the effects of a wizarding lifespan
especially when a story contains an inheritance. Assuming a life span of 150 years, and assuming that witches have the reproductive limits of Muggles, then say, outer edge, 40 years worth of childbearing, which means there is still two thirds of their life left when they are done with children. (Magic, I know, could change the parameters, but hey. Go with me here!) If one's parents are living as long, that means you would not inherit in the natural order of things, until your parents pass on. Which means you would be anywhere from 90 to 130 when that happened.
Inheriting earlier means your two parents came to grief by means of disease or violence. Stories where wizards inherit at 20, 30, 40 sort of ignore this subtext. One gets the impression that death by violence/accident is common in the wizarding world, what with splinching and dark lords and all, which means you had more of a chance of dying before getting your inheritance, too. More of a chance of inheriting from some strange great-uncle you never met.
Anyway, without inheritance coming for 100 years, a young person is either going to have to make their way on their own, or get help from the family up front. Isn't there a word for a lump sum of money settled on a young person starting out?
This would explain the scorn for the large number of Weasley children, because they are not going to be able to start so many children out 'right' unless the reason they are so poor is that they have been saving madly to send each of the kids out with at least a token. The twins must have been a relief, in fact, as they seem ot be taking care of themselves.
Anyway, I find the idea interesting that with a longer life span, it's a much longer period to be with one person. Muggle marriages have a large number (half?) not make it to the point the kids are grown. Imagine trying to make a marriage last 150 years! Maybe the kids inherit early when their parents can't stand each other anymore and....
It seems to me that at the point where the kids left, a lot of wizarding marriages would change. Roles would change.
Come to think of it, one could inherit from your great-great grandfather directly if your dad and grandfather were dead, but chances are the money would have to be difused among quite a few of his decendents. So one might want to limit the number of kids you have so that the money/power would come in a more direct path. Which might explain the Malfoys and other purebloods having only a few children. Lucius probably offed his own dad to make the arrival of his inheritance a bit more timely.
Anyway, the story idea is this. Wizarding convention has it that one must first marry and have children. Support the blood, like. And when the kids were grown, only then could you split that marriage and form another with your same sex. Earlier if it is mutually decided upon. I'm thinking of a sad Ginny putting her youngest on the train to Hogwarts and then going to the law-wizard and setting Harry free to go to Severus. Done right, it could be quite angsty.