Bilbo is said to have been more adventurous than most hobbits because of his mother's side of the family. Peregrin Took is a bit foolish and this, also is attributed to his "Tookishness." Not only is he a Took, but a "fool of a Took" which makes it so much worse. So what about this family makes them such oddballs in Hobbit Society?
I know about the passage that says there was a marriage once upon a time to a fae, but it is followed by another statement saying this was just rumor. While, this could be a device that actually gives the answer in a package realistic to the idea of Bilbo writing this himself, I wondered if there was any other canon explanation.
It was often said in other families that long ago one of the Took ancestors must have taken a fairy wife. That was, of course, absurd but certainly there was still something not entirely hobbit-like about them, and once in awhile members of the Took clan would go and have adventures.
The Hobbit, J.R. Tolkien pg. 2-3.