You are not born with a defined sexuality. It comes to you, unconsciously during your childhood. Your pointed in a a certain direction, but it does not define it. It leaves you with choices which you may, or may not choose to acknowledge.
Events from the past can be stored in the very prostate of your mind and may surface at any time. You are an adult, you have free will. What you do with these choices is up to you. Some choose homosexual relationships as they find this leads to an internal balance, an inner calmness. There may have been an absence of male love during your childhood so as an adult you can balance that. Satisfying yourself sexually is the key that opens the door to your heart’s desire. While you may be attracted to sex with someone of the opposite gender, as what is opposite can be balancing. But, even a slight change in your sexual energy can lead to a different desire. If this pushes you towards a different experience that fulfills your particular needs at that time, that is the very essence of you.