Harry Potter star Robbie Coltrane turned down the chance to research his genealogy on TV because he was convinced he would learn nothing new.
The heavyweight actor was asked to trace his lineage on U.K. family history series Who Do You Think You Are? but he is so passionate about his Scottish roots, he has already done his own family tree investigation.
He tells Britain's The Sun, "They asked me to do that Who Do You Think You Are? the other day and I said I know exactly who I am. I said, 'I can't learn anything I don't know already.'"
Coltrane reveals he is a descendant of notorious cattle thieves, while his more recent ancestors were religious workers.
He adds, "My great-aunt Greta was a missionary in Africa and my great-great grandfather on my father's side was a firebrand minister. How we have fallen! She wrote a history of my family going right back to 1520, I think it was.
"She discovered an awful lot of my forefathers had made a lot of money from rustling cattle off the English, because we came from the borders and a lot of the male members of the family were hanged. That's when she was a very respectable lady and she said, 'I think we've found out enough.'"