Wow, i think there are some wonderfully thoughtful and articulate responses here. i love this community!
As i see it, words are not the thing they describe, they're just a static point of reference in a fluid world. i really appreciated the first time i heard sexuality explained as a "spectrum," because it more accurately described my experience than the patriarchal notions i was raised with. But, like others have expressed, a linear spectrum doesn't contain/describe all the possibilities (or realities?) of sexuality.
i have some pretty distinct memories of my sexuality growing up, here's some "dissecting" of my own 'bisexuality.' Though i don't recall ever hearing or knowing the word "bisexual" growing up.
As far as i can remember, my first crush was on Marylou Thornburg in second grade. At the same age, there was also Craig and Gary, but those feelings happened in an era and culture that rejected same gender attraction. i remember Mary and me expressing our affections for one another, we connected. i hid my feelings for Gary, and when it came to Craig, i bought a shirt like his to copy the way he dressed.
When i was in third grade, i met Rita while roller skating on the sidewalks of my neighborhood. We would roller-skate hand in hand and talk about getting married. She kissed me (just a peck on the lips) in my back yard, my back against the the clothes line pole.
In fifth, it was Susan McConnell. I pined for her and wrote love songs about her, but never approached her... she seemed uninterested. i wore my sweater the way she did, buttoning only the top button and was chided by another kid for wearing my sweater "like a girl." One day i was at the park watching other kids in the swimming pool and i looked up and she was standing right next to me, i swooned and she didn't even notice me, i ran away.
There was also a Mary at church in 5th/6th grade, but also Mark. Mark and i were inseparable, we slept over each others houses just about every weekend. There was also Perry and my cousin Tommy. And Randy. Randy lived across the street and i cried my eyes out when he rejected me and became part of a rougher neighborhood crowd.
In 7th grade, at 12 years old, i somehow learned the word "homosexual," and realized in some way that it described me and my feelings for other guys. i remember going to the library and fearfully looking up "homosexuality" in the card catalogue. i was petrified that someone would notice me in the "h" section and find out my secret feelings. The only books i found were medical books that all informed me that my feelings were "sick" or a "disorder." That was the age where i gave my feelings a name and began to learn how to knowingly hide, but i don't remember thinking of myself as homosexual, just my feelings? Maybe because that is how all the literature put it? I.e., "homosexual" was a condition, not a state of being.
As i came of age sexually in high school, my emotional connections were with girls and boys, but my sexual attraction, or fantasies when i masturbated, was about guys. my first wet dream was of a guy i barely knew, Randy Lay. The dream was completely romantic, i dreamt that He kissed me. It was a full on mouth kiss, but was slow and non sexual. Funny, i had barely noticed this guy and had not really thought of guys romantically, not with this kind of force or feeling, but wow, my sub conscious sure knew how to feel and act. i was 14. i liked girls, but didn't think of them sexually.
i also became religious at 14 and began to repress and suppress my sexuality in earnest. i had already decided by the books i had read, and all the other cultural cues i experienced to date, that my attraction to guys was "sick, wrong, deviant, etc.," so acceptance of my sexuality wasn't even on my radar.
At 19, i was deeply religious, a fundamentalist christian sect. A girl i had known in high school was also a member. i had an attraction to her in high school, now both of us were out of HS and part of this religious cult (that's how i see it retrospectively). i spent a lot of time at her and her sisters house and one night while we were sitting on her back steps, i kissed her. She was the first (and only) girl i had ever kissed. We made out a lot over the ensuing weeks, i'd often lie on top of her and was usually noticeably aroused, but the thought of having sex with her never entered my mind. That same year, before we got involved, i had stood up in a church meeting and "confessed" my attraction to guys (as part of my effort to "get free" from it). She was there, but no one at that meeting really understood the implications of my reveal, including the two of us. By our reckoning, and system of belief, there really was no such thing as "gay" or "bisexual."
We married about a year after my reveal and a few weeks into the marriage, i brought up the topic again, thinking she would be my ally in my fight against this 'disease', 'sin.' Boy, was i ever naive, she was freaked and i back peddled and reassured her 'god' had everything under control, and went promptly back into deep hiding.
i stayed married to her for 31 years. i was able to function sexually with her. i love/loved her and enjoyed sex with her, though there was always something missing. i still continued to fantasize about guys (never women). After 5 years i ended up having sex with guys on the dL.
It's longer story (i know, it already is). After almost 35 years of trying to become straight, i (finally) accepted that my attraction to guys was not going away and that i couldn't simple deny it. my efforts to do so (attempting to adhere to my religious beliefs) were a dismal failure. i attempted to stay with my wife, but she was still of a mind that i had to change and i knew that wasn't going to happen. i told her if she wanted to be married to me, that this is a part of who i am, so she asked for a divorce.
After divorcing, there was a time where i wondered about being "bisexual." i had had sex with a woman for 30 years. i dated some really cool people.
One was a professor of gender studies, a German woman who had been a leader in the lesbian community in Germany. She told me that if some of her friends knew she had taken a ("sudden") interest in guys, that they'd probably kill her. She was awesome, and i was attracted to her, but didn't really want sex with her, so she continued her quest elsewhere.
i also dated a transgender (FtM) person for awhile. i learned a ton, but sexual attraction wasn't there either (whole other story, but i couldn't get past the sense of this persons gender being woman, even though i cognitively accepted their identity as a man).
i've had lots of opportunities to be with women sexually since being divorced, but to date, the only woman i have ever been with is my former wife. We had a very active sex life, but looking back i realize that it was pretty much about her, not me. Which is not to say i didn't like sex with her, i did. But sex with her was different than it is with me and guys. i derived most of my pleasure from being good at giving her pleasure. That was pretty much the focus of our sex life. She would even describe sex as me "pleasuring myself with her." In other words, her pleasure, and my pleasure, were both my responsibility.
While in the marriage, i grew to resent her for 'making' me responsible for both of our pleasure, mostly because i was starving. i don't anymore because i have come to better understand the multidimensionality of human sexuality. i have learned/experienced that there are both men and women who 'identify' with and want that position of control. Simply put (well, sort of "simply"), she was a hetero sub bottom with a (mostly?) gay sub bottom.