For the record, I'm 27 and have been gainfully employed since leaving college five years ago. And I'm married and live in a home that I pay for, and am nearly finished with a postgraduate degree. I'm definitely an adult. There are still days, though, that I feel a bit like a fraud - I still feel a bit naughty when I occasionally leave my shoes on indoors or eat popcorn for supper instead of cooking.
Just now, though, I feel like a Grown-Up who has Good Neighbours. Earlier today we had a knock on the door and opened it to discover our downstairs neighbour and his 2.5-year-old daughter. It transpired that the child wished to bake, but there was no flour in the flat. And given the weather, her very sensible parents decided they didn't want to traipse outside in the wet to go to the shops. Baby A informed them (and the rest of the building, actually) that this was a Major Tragedy and should be rectified Right Now, Thanks Awfully. So upstairs they toddled to borrow some flour. We've always got flour, since the spouse and I are both rather keen on baking, so we handed them a 500g sack and away they went, happy as Larry. Just now they brought us back the remains of the flour and a plate of freshly baked cupcakes. We've thanked them profusely and sent them home with a bottle of spouse's homebrewed elderflower champagne.
I'd always imagined having a sense of community and friendship with my neighbours. Looks like I've got it.