Sexuality isn't black or white . It's like a sliding scale with varying degrees. It has been because of taboos imposed by societies that ignorance remains so rampant. There are people who are completely straight. Then there are people who can look at the same sex they are and feel aroused with no desire to actually act upon it. There are people who only want to have slight sexual acts with their same sex. There are people who can enjoy full on sex with their same sex but can't attach emotionally. There are people who can fully sexually enjoy both sexes and attach to either sex. And of course there are people who are completely gay. There are people attracted to people who have the physical attributes of both sexes. Shaming has ruined the happiness and lives of many many people.
I was very happy the day my youngest daughter came to me when she was about 18 and told me she was bisexual. She was afraid to tell me because she loves me a lot & was afraid of a negative reaction. I just told her " That's cool. Be who you are. I've had sex with women. I just don't emotionally attach to women & this is our little secret now. " She cried. She was relieved that I didn't judge her. She has been in a relationship with a man that is very serious the last 3 years, but if that ever changed I would love her all the same.
edited: There's a lot of stuff I left off here. Like there are people who never attach to anyone and some that are incapable of loving any partner they have in any relationship. Lot's more stuff. It's not an either/ or thing..