This morning, I met a chap whose surname is Darwin. He'd come to quote for some work we need doing on the house. I was dying to know, so I asked the obvious question: "Any relation?"
"We don't know, but we've always assumed we must be," he said.
How could you not know? With a surname like that, how could you sleep at night, not knowing for sure whether you were related to the greatest man ever to draw breath? You'd find out, wouldn't you?
Postscript: I have since learnt that Darwin visited relatives while he was staying in Ilkley, so the likelihood of the chap I met being a relative himself sounds even more plausible.