Much of this may sound like old news to you. This post is the culmination of conversations I've had recently.
You may be aware that the argument has been made, and in some cases is still made, that homosexuals "chose" to experience same-sex attraction and to engage in same-sex sexual relationships, and that they could (and should) choose to become heterosexual. Part of the task of the queer movement is to assert that sexual orientation is not a choice. I can't prove anything, but I generally agree that we have little to no control over how our sexual orientations develop, and that we can't train ourselves into another orientation.
We can, however, choose our identities. Our identities change as we learn about ourselves or as our life circumstances change, and this is true not just of sexual orientation but in every facet of life. For example, if you lived in Arizona for ten years and then moved to Ohio and resided there full time, you'd become an Ohio resident and no longer be an Arizona resident, though you could still identify as someone who used to live in Arizona, if that was meaningful to you. In terms of the identity you choose for your sexual orientation, that may change as you discover parts of yourself you hadn't explored before for whatever reason. A lesbian identified person could change their identity to bisexual, for example, upon discovering that they are capable of being sexually attracted to a male. This person's orientation didn't necessarily change --they were always bisexual but weren't aware of it, what changed was a new experience and the decision to incorporate new knowledge into an identity.
It's also perfectly legitimate, in my opinion, for the person in this example to maintain their lesbian identity even if they have and recognize this new experience. There are many reasons why someone might choose to identify a certain way regardless of how well they "conform" to the assumptions of that label. What matters when choosing an identity for yourself is how well that identity serves your needs.
I talked about this today with a friend who was questioning asexuality. When deciding if it's OK or right for you to call yourself an asexual, what you should really be asking yourself is how identifying that way will enhance your life. If calling yourself asexual makes your life easier to understand, if it helps you think about the boundaries you need to lay out in relationships, or to clarify your emotional and other needs, then use it! It doesn't matter so much whether you conform to a particular definition of asexuality. Deviating is OK, you don't have to force yourself to live any particular way or judge yourself if the way you experience your sexuality changes. You can choose to call yourself asexual if that identity will serve your needs, and if someday you find another identity serves your needs better, you can change it!
Identities do not describe a person in their entirety, they just help us to establish some basic things so we don't have to keep coming up with new words for what we are every time we speak. Everyone has multiple identities, and every person has different attitudes about those identities, needing them for different reasons. Let's say someone tells you that they are a Christian. You can assume that they believe in God and believe that Jesus Christ is the son of God, but just hearing that a person identifies as Christian doesn't mean you know what parts of the religion they follow or how they worship. Another example, if someone tells you that they are French, that doesn't tell you where in France they are from or how they feel about French politics or anything really except perhaps their citizenship or residential location. Identities simply form places for us to compartmentalize our lives and make it easier to converse and get to know each other. Of course, identities are also frequently misunderstood and used against people to oppress them, but having an identity in and of itself shouldn't be oppressive. If your identity doesn't describe you in any way and you can and want to change identities, do it.