George,
Since I think you have the most similar situation as mine on the board, I would like to ask you just a few questions to help me figure out if there are things that are hydro or hereditary related for me.
First off, I've been the same weight since I've been 13. I usually range between 105-120 lbs. My mothers family is bigger framed and my fathers is thin like me. I was always curious if I can't gain weight because of hereditary, or is my body feeding off any water produced, which causes me to stay thin.
Also, I've always had low blood pressure. Both of my parents had high blood pressure and I feel like an odd ball. Is my blood pressure low because of hydro? Maybe.
I'm curious if you have any of these issues, or maybe others that you wonder are hydro related.