There is no consensus among scientists about the exact reasons that an individual develops a heterosexual, bisexual, gay, or lesbian orientation. Although much research has examined the possible genetic, hormonal, developmental, social, and cultural influences on sexual orientation, no findings have emerged that permit scientists to conclude that sexual orientation is determined by any particular factor or factors. Many think that nature and nurture both play complex roles; most people experience little or no sense of choice about their sexual orientation.

American Psychological Association

American Psychological Association, "Answers to your questions: For a better understanding of sexual orientation and homosexuality", 2008. 

Angelina Jolie stars as Gia, a gorgeous Philadelphia native who arrives in New York City to become a model and immediately makes an impression on high-powered agent Wilhelmina Cooper (Faye Dunaway). Gia's fierce good looks make her a star, as does her willingness to pose nude. Gia becomes entangled in a passionate affair with a photographer's assistant, Linda (Elizabeth Mithcell), but Linda is more conflicted about her bisexuality, driving Gia away and fueling the model's craving for mood-altering drugs.