Sexual Orientation is an enduring emotional, romantic, sexual or affectional attraction to another person. Sexual orientation exists along a continuum that ranges from exclusive homosexuality to exclusive heterosexuality and includes various forms of bisexuality. Bisexual persons can experience sexual, emotional and affectional attraction to both their own sex and the opposite sex.
Sexual orientation is different from sexual behavior because it refers to feelings and self-concept.
Persons may or may not express their sexual orientation in their behaviors. In most people, sexual orientation is shaped at an early age. There is also considerable recent evidence to suggest that biology, including genetic or inborn hormonal factors, play a significant role in a person's sexuality. In summary, it is important to recognize that there are probably many reasons for a person's sexual orientation and the reasons may be different for different people. No, human beings can not choose to be either gay or straight.