This is our second post on defining homosexuality. One of the issues that we have to face is how we think about same-sex orientation and choice. Is same-sex orientation a choice or not? My own view of the matter is that our sexual orientation is not really a choice in so many terms. I know not all agree with this, but my own reading and discussions lead me to the conclusion that same-sex desires are not something one chooses but something that one discovers to be true about herself or himself. Heterosexuals do not really “choose” to be heterosexuals; homosexuals do not choose to be homosexual.
I really like Chad Thompson’s book, Loving Homosexuals as Jesus Would, and here is his (a recovering gay man’s) own observation:

Homosexual attractions are not genetic or chosen; rather, they are developed during childhood, usually in response to a lack of affirmation from and identification with one’s own gender. Because this process is unconscious, it’s not fair to say that lesbian and gay people “choose” to be that way.

And again:

Anything that creates a sense of disconnection between a child and his or her gender, consciously or unconsciously, can stifle gender identification and potentially create homosexual attractions. [He lists some common influences:]
1. Rejection by one’s same-gender parents or peers (real or perceived).
2. Sexual molestation.
3. Temperament (a child’s natural inclination to be sensitive or artistic vs. athletic or mechanical).
4. An abnormally-close relationship with one’s opposite-sex parent.
5. Lack of identification with one’s gender.
6. Genetics.

But, each of us does choose how to live out our sexual lives (some choose to be faithful; some do not). So, I think our orientation is not really a choice; I think our sexual behavior, which expresses our orientation, is a choice and we are responsible for it.
Along this line of “choice,” though, I don’t agree that we can argue from “the way we are” (however that might be) to “this is the way God made me.” The only thing we can say about “how God made us” is from biblical texts that speak of “how God made us,” and those texts are all rooted in Genesis 1–2 where we find that God made humans to be “male and female.” In other words, while I know why some say “this is the way God made me,” a consistently biblical view of such a claim falls short of what is often said. (In other words, I don’t think it is fair to move logically from “this is the way I am” to “this is how God made me.”)
My last point is a plea: we should refuse to use analogies to sins when we are genuinely conversing about homosexuality. I have myself sometimes fallen into this and it grieves me because it violates reasonable conversation. Let me explain: I might say in the context of this discussion that “I think impatience or anger or violence is my natural reaction to given situations and that is how God made me.” By using such analogies, I prejudice the case and strike others as prejudicing the case. For the sake of argument, analogies ought to be avoided as often as possible.
I’ve seen some of this in the Comments; my plea is that we will learn to talk about this issue more reasonably by avoiding such analogies.