I think that this effect will have ended with modern gender equality. Each family has on average only one male child per generation, so if you consistently pass

I think that this effect will have ended with modern gender equality. Each family has on average only one male child per generation, so if you consistently pass the money down to your son (the child with the same surname as you) then it will last a long time. But these days it's more common to give money to all your children, so it's halved at every generation.