I was one of those kids who had to grow up too early. I had a younger brother and my dad left us when I was about 4 so I guess I was trying to be a grown up replacement from then on. That period when I let myself turn back into a child was difficult to break out of but I know that, spiritually, it was important to let it happen.
One other thing: people never completely 'grow up'. We all have a 'child in us' and it is very much a blessing to be 'in touch' with that part of us. People who lose touch with their 'inner child' can become very unhappy. Its a question of balance I suppose. . . .