Bisexuality is a sexual orientation. Bisexuals are sexually attracted to more than one sex, gender or gender identity though not necessarily simultaneously, in the same way, or to the same degree.
A review of several studies on LGB population by the Williams Institute concluded that bisexual people comprise about half of LGB people in the United States (Gates 2011). Among the surveys reviewed was the National Survey of Family Growth (NSFG) which placed total percent of adults who identify as gay, lesbian, or bisexual at 3.7% (2.3% as bisexual and 1.4% as gay or lesbian) in 2006-2008.
In the NSFG survey, roughly 3 times as many women (5.5%) as men (2%) identified as bisexual. This is consistent with other surveys or studies where women are substantially more likely to identify as bisexual than men.
Despite the fact that bisexual individuals make up a significant part of the LBGTQ+ population, they face pervasive biases within their own families, communities, in the educational environment, as well as within the workplace. And studies have shown that straight-identified people often have more negative perceptions of bisexuals than they do of gay men or lesbian women.
Bisexual individuals are often discriminated against because of misconceptions about their sexual orientation. For example, some think that bisexuality is a phase for curious heterosexual individuals or confused gay or lesbian individuals which leads them to disregard or invalidate expressions of bisexual experience.
These misconceptions are at odds with recent research that has shown distinct differences between bisexual arousal patterns and arousal patterns among both homosexual and straight men and women. In one study, bisexual women and heterosexual women both showed reactions to male and female sexual stimuli, while homosexual women reacted only to female sexual stimuli (Safron 2018). In a companion study, bisexual men reacted to both male and female sexual stimuli, while heterosexual men reacted to female stimuli and homosexual men reacted to male stimuli (Safron 2017).
Resources
Bisexual Resource Center (BRC)
National bi+ organization in the U.S. that advocates for bisexual visibility
https://biresource.org/
American Institute of Bisexuality (AIB)
Education and research into bisexuality
http://www.americaninstituteofbisexuality.org/
Bisexuality FAQ
https://bisexual.org/qna_categories/bisexuals/
Resource list from GLAAD
https://www.glaad.org/bisexual/resources
Research
(2019) Single Bisexual Men’s and Women’s Perceptions of Acceptance in the LGBTQ Community, Journal of Homosexuality,DOI: 10.1080/00918369.2019.1618645
Safron, A. et al. (2018). Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Women Scientific Reports. 8, 673; https://www.nature.com/articles/s41598-017-18372-0
Safron, A. et al. (2017). Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Men. Scientific Reports. 7, 41314; doi: 10.1038/srep41314
Gates, G. (2011). How many people are lesbian, gay, bisexual, and transgender? The Williams Institute whitepaper. https://williamsinstitute.law.ucla.edu/wp-content/uploads/Gates-How-Many-People-LGBT-Apr-2011.pdf