Not, for example, in the terms "I am gay," but they begin to consciously realize as they grow into adolescence that their interests sometimes differ from those of their peers, not only socially but sexually as well. As they become more aware of that difference, most attempt to conform and change their behaviors, whether they are large or small, to fit those around them. The awareness that their thoughts and actions don't coincide creates tension, referred to as cognitive dissonance. According to the cognitive dissonance theory, in order to relieve that tension, people often try to bring their attitudes in line with their actions. Many times, a gay teen attempting to change their non-sexual actions to better match those of their peers succeeds, and develops genuine interests and enjoyment out of that social interaction. However, their sexual preference is rarely, if ever, changed very greatly.
Eventually a gay teen becomes consciously aware of their difference. With that awareness, usually comes fear. From childhood children are aware of homosexuality, but very rarely in the positive sense. Many groups of children use the word "gay" as a derogatory label directed at others they view negatively, in order to demean the person through the meaning of the word itself. To accuse someone of being gay is to label them an outcast, or to be "un-cool". Being the social creatures that we are, becoming labeled an outcast is not uplifting. .
At this point, fear is a large factor in the life of the adolescent. Most are horrified by the thought that their parents might find out. Many are also ashamed that their attitudes can't coincide with the actions of their parents, who are usually the one or two main figures thus far in their lives. So, usually life begins to become a struggle to internalize their true sexual feelings while upholding the appearance of normalcy. That struggle, in addition to the usual hardships an adolescent faces, can make for a very discouraged teenager.