Coping with such a child would be difficult for any parent, but it was especially frustrating for his father, one of the world’s leading neuroscientists. Henry Markram is the man behind Europe’s $1.3 billion Human Brain Project, a gargantuan research endeavor to build a supercomputer model of the brain. Markram knows as much about the inner workings of our brains as anyone on the planet, yet he felt powerless to tackle Kai’s problems.

“As a father and a neuroscientist, you realize that you just don’t know what to do,” he says. In fact, Kai’s behavior—which was eventually diagnosed as autism—has transformed his father’s career, and helped him build a radical new theory of autism: one that upends the conventional wisdom. And, ironically, his sideline may pay off long before his brain model is even completed.