it all depends tho, doesnt it? One of the main groups I work with at the moment is young carers, teenagers who have been looking after (usually) their parents, often on their own, and who have been doing for years. They tend to be pretty good at empathy, and tend tp be rather more mature than other teens their age. Many of them are actually more mature than various 20odd year olds that I've known.
The point being, you can't really talk about '13/14/15 year olds are like this/have reached this stage of development', because they really are all over the shop, some are still astoundingly childish, some are astoundingly grown up.