The new series of Who Do You Think You Are? premieres tonight on BBC One. The first episode is about the ancestors of the television presenter Zoe Ball. I adore the schadenfreude of witnessing a wincing luvvie discover their ancestor was an irredeemable scumbag. My family are not free of moral stain. Court records attest that my great-great-grandfather, a publican from South Wales, once furnished a pint of beer to a punter outside licensed hours. The devil!

My late grandparents, straightforward Welsh Methodists, never told me about lawbreakers in the family. News that one of us might have been a bit dodgy back in the day shook me. I told the story to an acquaintance, which prompted some drastic perspective: ‘At least you haven’t got Hitler in your family.’ Indeed, some people do.

Adolf Hitler died childless, but he had half-siblings who reproduced – his half-brother, Alois Hitler Jr., and half-sister, Angela Hitler. Alois was the father of Liverpool-born William Patrick, who changed his name to William Stuart-Houston after the war. Peculiarly, none of Stuart-Houston’s four sons had children, and three never married.

We look to the past to explain the failures and successes of the present