Why Many Who Believe That “All Are Born Sinful” Hold That “None Are Born Gay Or Trans”? Many Protestants, though not technically or officially Reformed, are nevertheless strongly influenced by Calvinistic theology; as such, they espouse the doctrine of total depravity, teaching that all men are born under the power of sin (Psalm 51:5).
However, a large part of them are also politically active, and I couldn't help but notice that this important segment (ascribing to conversion therapy and associated with the ex-gay movement) also holds to the notion that no one is born gay, trans, etc., but rather, they embrace certain discarded psychoanalytical ideas about the latter being a product of upbringing; in other words, of nurture, rather than nature. Granted, I am not exactly arguing that all sin is inborn, and that no vices are learned or (self)taught, but the (religious) zeal with which they (communally) cling to this opinion seems to border on dogma.
My bewilderment stems from the (apparent or perceived) contradiction between the two views. Am I missing something ? If so, then what ? (Your contributions are greatly appreciated).
I can only speak from a UK context, where there isn't a Christian right like there is in the US. But I think the way the church has handled issues of sexuality is similar. In the last 10-20 years, the church here has come a long way in understanding sexuality. Organisations such as Living Out have been set up within the past few years, helping people to put the pieces of the Bible together.
Unfortunately, I think many in previous years held to traditional Christian ethical beliefs without really holding to other fundamental Christian beliefs (e.g. total depravity) - the morality became divorced from the theology. What you ended up with was a kind of Pharisaism where sexual sin such as this was seen as particularly bad. It was much more common in the mid-20th century to see homosexuality as something that was chosen, and many church leaders have simply inherited this view without thinking through how it fits with theology.
This is why, for example, in Tim Keller's review of Matthew Vines' book, he says:

And when I see people discarding their older beliefs that homosexuality is sinful after engaging with loving, wise, gay people, I’m inclined to agree that those earlier views were likely defective. In fact, they must have been essentially a form of bigotry. [My emphasis] They could not have been based on theological or ethical principles, or on an understanding of historical biblical teaching. They must have been grounded instead on a stereotype of gay people as worse sinners than others (which is itself a shallow theology of sin.) So I say good riddance to bigotry. However, the reality of bigotry cannot itself prove that the Bible never forbids homosexuality. We have to look to the text to determine that.

I think this is what has happened over the past 10-20 years. Many organisations and churches who own the name &quot;Christian&quot; have been shown that, although they may claim to hold to views such as total depravity, do not think it through when it comes to issues of morality.
I should add that I think this is a sensitive and complex area because different people have different views. For example, in the UK, the Core Issues Trust do not describe what they do as conversion therapy, but they believe that it is sometimes possible for someone to undergo change in their attraction. And having a strong view of sin (e.g. total depravity) I don't think is totally incompatible with believing that aspects of our desires, including sexuality, are a choice. But I don't think that's exactly what you were asking!