Well, because I am straight (heterosexual), I dated men and I married a man. Because they are gay, my gay friends dated and committed to partners of the same gender, despite the fact that they experienced an equal degree of peer pressure from both our straight and gay friends. 

It is developmentally expected and normal that most young people engage in peer pressure about almost anything that has captured their attention, and my friends and I responded in expected and normal ways to peer pressure:  we responded with choices that were consistent with who we are.