I've never understood parents who kick their children out the second they turn 18 or as soon as they graduate high school. If a kid really wants to spread their wings immediately after leaving school, then good for them, but I wouldn't say that most teenagers, even adult teenagers, are 100% to take on the world without any help just because they're technically adults. That doesn't mean I think that high school graduates should just be sitting around their parent's house contributing nothing to society just because they have free rent. They should go to college or work or do an apprenticeship or something to set themselves up for success without Mom and Dad. I'm willing to bet that most parents who kick their kids out when they're 18 aren't doing it because the kids are lazy. It's usually because they aren't willing to be parents beyond what's legally required of them.