Kids

Think seriously about ever having kids.
In the olden days, you only had to worry about them till they were old enough to leave home (late teens, early twenties), now it's a lifetime commitment.
Spiralling house prices mean they might never leave, and if they do they get into a mile of debt and want to come back.
Don't think it's just mine, they all seem the same.
Want everything now, and don't think of future consequences.