Answer:
Because they are in a gang ( they are gang members ) . In those gangs, they are exposed to the things ( crimes ) that occur there. They don't get guidance on what is wrong and what is right. They think that committing crimes is a normal thing because they are surrounded by people that do ( believe committing crime is a normal thing ). Whereas other teenagers know what is wrong and what is right ( committing crimes being wrong , they won't do it ) . They have people ( parents, family , friends etc ) that are there for them and support them. Teenagers in gangs might not have that . So being in a gang is ( sometimes) the only way for them to feel accepted, and they feel like committing crimes like the rest of the gang members is the only way that they can do that ( feel accepted).