Innate bisexuality (or predisposition to bisexuality) is a term introduced by Sigmund Freud (based on work by his associate Wilhelm Fliess), that expounds all humans are born bisexual but through psychological development (which includes both external and internal factors) become monosexual while the bisexuality remains in a latent state.
Academically speaking, and what the research shows, yes. People are socialized to believe in a binary when in fact that's not how human sexuality works.
Nobody is 100% gay or straight, no matter what you think.
Nope. There are guys out there not into dick at all, and guys not into ***** at all. I hate it when people say everyone is bisexual, why not just accept there are some straight or gay people in the world and let that be that. It's a nice idea but that's just not how it is. (imo of course, I don't know everyone in the world).