I don't think people really "find themselves". I think it's more that they find something external that maybe answers some questions or reveals something about life that they previously hadn't realised or understood. Possibly some experience simply changes how they think and view the world.
There's a reason that "finding yourself" often involves travelling to a far away and unusual land, interacting with people who have a different point of view, or even stumbling across a book.
I think a lot of people "find themselves" when they go to university, or when they move out on their own, as this means they are outside of the influence of people who previously had the power to pretty much control what they thought and how they felt (not necessarily intentionally). Not mind control exactly, but we all know that parents, close family and old childhood friends can have a pretty strong affect on people, both positive and negative.
Perhaps some people cling to childhood and family so much, that it takes travelling to another country on the other side of the world, and being surrounded by people very different to themselves, to really have that growing up period in life.