That is a provocative question. The simple answer is yes you are bi. But it is more complicated than that. It has been known (or suspected) for more than 50 years now, but gay people were born that way. They are not mentally disordered or making a choice. All attempts at converting them have failed. Research has suggested that this orientation is at least partially due to high cortisol levels present in the mother during pregnancy at the time the brain is developing at about 10 weeks of gestation. It is also likely that there are genetic components. The causes are poorly understood.
In my family for example, I had a gay uncle who never married. I had a lesbian aunt, my mother’s only sibling, who also never married. Of my two brothers, the youngest is gay and married to his husband in Atlanta. There is a high incidence of being gay in our family, which appears to be due to more than just environmental influences. This conclusion is also suggested in the studies of twins.
By extrapolation it is reasonable to assume that being bi is also a fixed sexual orientation present from birth. We know that people experiment with their sexuality as they get older. Some people abandon the attempt. Others find that their sexual interests are broader than they first imagined.
In my case, I am a postop passable trans woman. I have three grown children. For most of my life I would have considered myself a heterosexual male. I did not have the slightest interest in sex with men at all. When I realized and accepted my transgender status, I had an almost overwhelming desire to be seduced by a man. It has never abated. I now realize that I too am bisexual (or more likely panromantic, demisexual).
Psychologists generally maintain that sexual orientation does not change with transition. Some are beginning to reevaluate this position and believe that it can, generally attributing it to higher levels of estrogen associated with HRT. In my case my obsession with men pre-dated any transition modalities. I had not taken the first hormone or had the first surgery. Research on this subject is still evolving.
So what is it? Is sexuality innate or can it change over time? It is not an area I have researched at length because it is unimportant to me. It is enough to know the kind of person I am and the kind of people I prefer for intimacy. I really don’t care about why. I wrote an article a couple of years ago about this called My Changing Sexuality. You can find it here on Medium.
If I had to speculate, I would probably say that sexuality is fixed for the most part from birth. Too much work has been done trying to cure and convert gay and lesbian people unsuccessfully to conclude otherwise. However, whatever one’s basic orientation, I think it is quite possible that certain aspects of sexuality can be hidden (whether merely unknown or suppressed by social or religious pressure), only to later be discovered through experience and/or introspection. It is also possible that it can change within a narrow range. But I do not believe that you can ever convert a heterosexual person Into being gay or bi or vice versa. I am virtually certain the mental health community would support me on this.
BTW, I did a fairly significant edit on my original comment. The substance is the same, but I thought my original effort was as poorly phrased as the comments by many who talk about sex assigned at birth. I felt like it needed tightening up.
