I can tell you that I'm 25, almost 26, and yeah - I'm still living at home. My parents at least are the types of people who let me be very independent, are very easy-going, and since the only 2 things they're taking care of are rent and car insurance (I'm paying my own bills, doing my own laundry, mostly buying my own food and paying all my college tuition) I really don't feel like too bad of a leech. At the same time though I am a senior, am going to a 4 year college which happens to be much more of a commuter school, and to be honest I love the lack of dorm life. It isn't my thing, never would have been, and to tell the truth I couldn't handle paying something like $3500 a year extra for room and board somewhere when I'm going to be living with somone I don't know who may be real disrespectul of my private space. My home is my safezone, it's where I decompress, its where I can actually have a chance to chill out after a long day of work or school, and I don't want any hostility or testing there. Having a friend live at my house back when I was 20 was actually an incredibly cool thing but then again that's having a friend move in who I know I can trust and who I can work out the fine details with pretty well - rolling a dice on that IMO is just plain stupid (then again in college all too often, unfortunatly, its essential).
I think it all really depends on the person anymore. Even though I tend to feel more than a little wierd still living with my parents, almost any NT my age who I mention that to reassures me the other way and tells me I'm incredibly smart for staying home and that they probably still would be as well if they could have.
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The loneliest part of life: it's not just that no one is on your cloud, few can even see your cloud.