He has pretty impressive credentials and it's clear he inspired someone in his life to rock at math. His daughter placed 3rd at national Mathcounts, won Westinghouse, was on the national Chem olympiad team, and has a PhD in math. She teaches for AoPS and there are articles about her on the website. Given his work with teachers and students in math circles, it's clear he has inspired many other students and served as a mentor to mathy kids for a very long time.
His website is amazing with tons of resources.
