I have a 15 year old daughter, the last teenager out of my 4 children. She is going through this stage. Peers influence her clothes, mannerisms, and attitude. She is a fairly easy going girl and is friends with different groups. Many of her friends are academically gifted but immature, others are artistically talented both musically and creatively but socially awkward, and the remaining group is athletic but not academically motivated. Each group doesn't socialize with the other making things very difficult. She really doesn't know where she fits in and who SHE is.
I was reading the domains of contingencies of self worth relating to college students and they also relate to middle and high school students. These students also depend on approval, physical appearance, competition, academic competence and family support. Self esteem depends on these characteristics. Eventually most adolescents discover their identity and self concept through self knowledge, gaining knowledge about oneself. It is a long rode but a journey everyone must take. Here is a clip you might enjoy. It should bring back memories of high school all over again.