Forget family hair genetics interpretation. These things skip, and seem random.
You need a real expert derm and maybe hormone Doctor who has experience.
If duast doesn't help, then at least save the crown.
Then do a transplant with as much donor as possible
Well if you would have consulted with a specialist hair restoration expert earlier at the time of shedding or hair thinning then your son would not have faced this problem. But, still, as there is a saying that "where there is a hope, there is a way". So, don't worry about this just consult with a trichologist soon to get the effective solution.
My husband's hair is thinning a little, now that he's in his mid-50's. My father started noticeably losing hair in his late 60's. Every male cousin around his age (on both sides) still has a full set of hair. That's what is so confusing!
Could you please tell me what DUPA is? The only thing I could find was that it meant A**. Sorry, I'm new at this...