If people are truly BORN gay or transgender, then the scientific and medical communities could and should be detecting these distinctions at birth, and fixing them immediately. Amirite?

Sexuality fascinates me, as I am sure is true with most people. We are sexual beings and creatures.
I am not a gay basher or transgender basher. I have a gay son, but he has chosen for whatever reason to not include me in his life. I split up with his mom when he was 6, and I know that had a lot to do with it.
Please do not think I have not done plenty of reading about the topic. If you wish to argue with me, at least provide substance and proof. I don't care what you "feel" or what the popular opinion is at school or among your circle of friends. I am still looking for answers to fully understand the issue. Most every study I have found and read, targets adults - so it is difficult for me to conclude that all of these people were a certain way or thing at birth. That is the purpose and point of my post.
If someone is born WITH or AS something, usually science or medicine can detect and determine it. But I am not naive or unaware of the fact that some diseases come later in life, unknown to anyone as to why.
All I am saying and asking for is the overwhelming consensus and proof from the scientific community to back and support the claims of someone being born with a sexual preference of disposition IN SPITE of the gender they are born as. Doctors still determine the gender of a child by penis and/or vagina. There is no pattern or new trend in the medical community stating "gay" or "transgender" at birth.
The picture is "Chaz" Bono who was born a female to Cher and Sonny Bono. Her birth name was Chastity. She has undergone breasts removal but not penis attachment. From what I have read, she/he is saving for the expensive surgery and has never felt totally comfortable with the surgery. She/he cites that going from vagina to penis is not as successful or easy as going from penis to vagina.
Either way, in my book, and where I came from, if you have a penis, you then can be called a man. No penis, no man.