Does your brother think he has a problem? Does he socialize with others and feel comfortable or is he anti-social? Do you recall when he was younger that your parents ever brought him to doctors to have him evaluated, or has this been done recently?
You can't force an adult to go to a doctor when they don't want to, but from what you describe, somethings do need further investigation by a heath care provider.
If you have a good rapport with your brother and/or parents, perhaps you can talk to them individually and convey your feelings about this, but ultimately the decision needs to come from your brother.
I'm glad you are a concerned brother. :-) Keep us informed.
Honestly, you sound correct, probably at least a deficiency in testosterone.
As far as I know, however, there are not many truly harmful symptoms of this. Provided that your brother does not experience distress as a result of his condition, I don't think you need to be too concerned. If your brother finds comfort in explaining it as being transgender, then he seems to have accepted his condition as how he will continue to be.
It is moving that you are concerned for your brother, but I don't think it is necessary.
There are problems with having a testosterone deficiency including high cholesterol, osteopororsis or low bone mass, loss of muscle tone, loss of libido and erectile dysfunction.
There is nothing wrong with being transgender.
However, I believe there is more going on with the OP as I mentioned above to his brother.
Are you a medical professional?
He has been extremely anti-social for years.
I blame myself for not forcing him to get diagnosed. He has now managed to convince my mother (who was always oblivious/in denial) that he needs to "correct" his gender. They are soon meeting a doctor to discuss the issue.
If he had previous sexual relationships, maybe I could trust that he knows what he's doing. But he never had a relationship of any kind, physically looks like a child, and is now indoctrinated by fervent armchair activists.
You can't blame yourself for your brother's problems. He is an individual that can make decisions. I realize that you are very concerned for him and only want what is best for him. Just by coming here and asking these question, I can tell how concerned you are, but please do not blame yourself or feel guilty in any way.
If he is seeing a doctor soon, perhaps you can go as well. If your brother allows it, perhaps you can also talk with the doctor privately and let him know your concerns.
You're right, it's out of my hands. It has become apparent that my input on the matter is neither required, nor is it wanted.
I will have to put my trust in the professionals who will be handling things from here.
I'd like to thank Foggy2 and Kouu for responding.
You are a good and very caring brother...remember that. Although he nor your mother may not realize that now, perhaps someday they will. But in your heart, you know that you have tried your best to help and love him. Continue to try where you can. Maybe someday things will change and your brother will see that he is loved by you instead of pushing you away. I wish you and your family the best of luck.