Read the following paragraph from "adolescence and personality": the dramatic changes that characterize puberty present the adolescent (an individual between puberty and adulthood, a teenager) with serious psychosocial (psychological and social) challenges. a person who has lived for 12 years has developed a certain sense of self. in adolescence, however, this knowledge of self is challenged. as has been discussed, the rather sudden bodily changes in this period are accompanied by equally dramatic changes in thoughts and feelings. thus, not all of the assumptions (beliefs taken for granted or assumed) adolescents held about the self in earlier stages may still be relevant to the new individuals they find themselves to be. because a coherent (connected) sense of self is necessary for functioning productively in society, adolescents ask a crucial psychosocial question: who am i? according to this paragraph, what often causes an individual to question her identity?

I believe that it has a lot to do with hormones (1) It is said a lot that girls are attracted to boys and boys to girls, but not much is said about homosexuality, especially in certain religious groups so if i girl finds herself liking another girl, she may ask herself, "Am I supposed to be a boy?" or "Am I boy trapped in a girl's body?" and as a result may stop talking to certain people. 
I believe it has much to do with how they are raised, and how much they look on society because certain individuals may know that some girls like girls and some boys like boys and that's just the way it, so if they find themselves liking a member of the same sex, they may just accept it and say, "This is me."  One may also question your identity because it's also the little things that make someone who they are. For instance, one may be looking for a catchphrase like your best friend,might be looking a particular facial expression when bored, happy, sad, or even puzzled, one may be seeking a logo for your own imaginary toy shop, or trying to make a signature, or just make anything your "trademark"
I hope this helped you, comment if this helped you or if you want more information.

Where is the sentence? be more specific so we can you