Bisexuality is universal. From a biological standpoint, have same-sex behavior do exist in the nature of the animal, like a dog in the growing process, need to transition from same-sex sexual behavior to the opposite sex sex, the rabbit in the environment of the opposite sex did not exist estrus, will choose to gay as a sex object, because only the Monkey King has the right and a female monkey monkey, so usually male monkey estrus, can only masturbation or by same-sex civil actions to solve the physiological needs, so the animals there are heterosexual, gay and bisexual animal also exist.
In comparison, the human is more complex, the reason is that, in addition to biological, human is social attributes, including factors such as emotion, environment, and is also a social animal, decided to people have the behavior of biological properties, and the existence of the social attribute. Pairs of sexual behavior, from the exterior appearance and behavior, because essentially bisexual men or women. Really bisexual people, reflect on the feelings about gay and straight, without any increase in any factors, including emotional color and interests, to be able to interest with sex appeal, the attraction.
Modern society, people of biological blurred, a lot of time or a lot of people don't pay attention to the points is not clear what he belongs to the biological properties of animals, as a result of social factors in the location more and more important in life, so the social property instead more dominate people's behavior and sexual orientation, including emotion, environment, the objective conditions, prompting more social emotional sexual response orientation. Someone had a very fleeting heterosexual pursuit and performance, but discouraged because of failure, and embraced gay, finally completely become bisexual men and women. Now life pressure, so in the pursuit of choice when tend to be simple, expect more easily communication, prompt their sexual behavior tends to social attribute selection.
Usually bisexual because of had the feeling after just can have sex, is the need to experience a process of emotional condition factors might have same-sex sexual orientation, absolutely won't have sex easily to occur. Bisexual people pay more attention to the feelings, rather than sex, they will be very happy to meet bisexual people. That claim to same-sex can, can with the opposite sex can again, and have no sexual behavior problems in existence, it is sexual abuse, also is the way to tentative behavior diversity, in essence is actually straight. Bisexual, in the true sense actually objectively impossible can literally on the bisexual sex, he produced by sexual behavior is absolutely the main direction of sexual orientation, both under the specific factors of sexual orientation.