[ecomcon]

At the age of 5, Potter tried to climb the stone wall that surrounded his family's temporary home , but fell on his head, she said.

Alrighty then.

[Wheelman81]

I saw the part about landing on his head at age 5 and thought that explained a lot. (Among my circle of friends we would incredulously ask someone who did something stupid: “What, were you dropped on your head as a child?”)