I saw a very schoking (danish) documentary about kids who had "taken over" the household because their parents was alcoholics. It was called "The little grown'up's" and really scared me. It showed a 12 year old girl who looked after her 9 year old sister, made her lunch pack and sent her to scool before she herself went, then after scool she did the shopping, cleaned the house, collected her sister, paid bills, cooked dinner, washed clothes etc.
All that time her mother (who was single) lay on the couch recovering from last night or was starting the next booze trip. Fortunately they had a neighbour who was a sort of "spare granny" and looked after them but she was retired and had limited resources. In the end the kids was taken from the mother(or rather the other way round) and they were given the chanche to be kids.
We saw them some months later and the change was dramatically. Gone was the woman running the household and instead there was a normal 12 year old girl playing with dolls and similar.
Another example was a 13 year old boy who also tended for his drunk mother. HE stayed with his mother but was given massive help. In the end he said "and now i have been allowed to finish scool". "I am very gratefull for that" That sentence gave me a shiver, that is NOT the way a normal 13 year old will express himself (and most woud definitely not be "gratefull" for being "allowed" to finish scool).
That to me is kids being "grown up" too soon.
The other problem with 12 year old girls wearing make-up, clothes with bare navels, piercings and all that is not less serious. It is like i heard a teacher say once: "Those girls are sending out false signals". "They are writing out dud checques". The trouble is that some pick up those signals and react to them in a way that those girls are not prepared for.