For the record, every physician at some point, takes a course called histology, in which you look at the characteristics and morphology(shapes)of all cells and structures in the human body, so every physician who has graduated from accredited medical school should be able to tell with some measure of authority, and high probability, what a pubic hair looks like!!!
If your brother's hair is also tapered, has he never had a haircut? A single haircut, will render any hair without a taper. I should think that he must look very strange with a head full of pubes?
People who do not know any better, should probably keep their analyses to themselves, as they have neither the knowledge nor the first hand experience to make such a determination as to the validity of a claim.