Jacobs has been described as “the virtuoso of the self-as-guinea-pig genre.” He has, for example, spent a year obeying – as literally as possible – the tenets of the Bible. He is also, as this enjoyable exercise will prove, your cousin. And mine. Because we are all “part of one big family”. This is, in fact, a light-hearted blend of popular science (the newest information on DNA) and sociology (the exploding genealogy industry).

“You have sixteen great-great-grandparents, but you probably share your last name with only one of them.” It’s written in that sometimes off-putting, populist American humour that is both self-deprecating and inoffensive, ie, there’s no edge to it. (I would love to see David Sedaris tackle the subject.) But his message is strong enough to overcome that, and he asks some good questions, eg, is “family” a bad thing, or, do the dead deserve privacy?

“By pointing out that everyone on earth is family, I’m hoping to de-emphasise the ‘tradtional’ family and embrace a thousand variations.”