Osteopenia In Men

I am a 43 year-old father of three children. At puberty my bones and muscles never really developed as a normal man and I do not get a lot of acne. I have thinning of the bones of my mother, my father and my brother. In 5'9, I am very thin (~ 11.75 "bicep) and the ring size of a woman. I weigh ~ 146 lbs. I am the greatest man in my family. My arms stretched over my height nearly 4 inches. I have less body hair than all other men in my family. The hair recession arrested ~ 26 years. I had prostate problems (swelling, infection, pain) on & off for last 12 years, although it improved since I stopped drinking milk ~ 4 months ago. ~ 6 years ago I was diagnosed with osteopenia. I also have a minor scoliosis. My testosterone level recently measured at 610 (blood test). I lifted weights for many years, but can not get the large muscle mass. I do not easily gain weight around my abdomen. My bones / muscles are very similar to a larger version of the body of my daughter 9 years. Endocrine or another disorder?

You seem to be a normal variant of the human condition. You need to take medication for osteopenia, though.

Perhaps Kleinfelter syndrome.