The urinary tract, including the kidneys. They also handle male reproductive parts. Nephrologists specialize in the kidneys.
The OP description sounded more nephrology because of the mention of genetics, but hard to say.
Quick overview of differences:
https://www.bostonkidney.com/2019/08/09/nephrologist-vs-urologist/#:~:text=Choosing%20between%20a%20nephrologist%20and,issues%20related%20to%20the%20kidneys