@Kim...In Christian humility and sincere respect, I think that the "scientific and sociologic" jury is not yet unanimous regarding the question of sexual preference or gender identity being innate or by choice. But regardless, and again with respect, I think that this is actually irrelevant to the issue at hand.
What I mean is that as Lutheran Christians, we believe in the doctrinal position on total depravity. In other words, due to the fall of man through original sin, we are all by nature children of wrath. Our nature, being spiritually dead in and of itself, is definitely not a choice we had the opportunity to engage in, and is with us from conception onward - and for which we are accountable and responsible. In other words, even here where "choice" played no part at all, it does not therefore exonerate us from the standards of an Holy God, with just and righteous judgement.
The propitiation for ALL sin, as you know, is our Savior Jesus Christ. His atonement pays for all sin, for all time. Yet if the scriptural position on homosexuality is that it is sinful, because we now walk in grace we must not advocate it, just as we would not advocate stealing or lying (which stem from the same depravity) as being right and natural because they're perhaps debated as choice or innate.

Luther did not advocate that Rome move from archaic teachings, he advocated that they move from WRONG teachings. There is always a risk that those outside the church will dismiss it as being closed-minded, bigoted or discriminatory, but it's actually none of those. It is a principled and yet compassionate stand that does not stand against those who self-identify as LGBT etc, but stands compassionately with them under the empty cross.