Actor David Tennant is to marry actress Georgia Moffett. That news is fairly straightforward, albeit devastating for several single women I know.

But the type of viewer who gets confused between actors and the televisual roles they play should just give up now. You see, the pair met during the filming of the 2008 Doctor Who episode The Doctor’s Daughter. Tennant, of course, played the Doctor, while Moffett played his daughter.

Well, sort of.

The character Jenny was in fact created by inserting the Doctor’s hand into a progeneration machine, a device that took a diploid cell (containing copies of chromosomes from both of the Doctor’s parents) and split it into haploid cells (which contain one set of chromosones), using this to create a new life form: a “daughter” who was the Doctor’s direct offspring, but did not have a mother.

(Please note that even though scientists have never achieved the exact same thing with humans or animals, Japanese researchers were able to use this haploidisation a few years ago to produce a baby mouse with two biological mothers and no father.)

However, if you thought this only left the confusion of what race the artificially created daughter of a half-human, half-Timelord has, think again.

To make things even more muddled, Moffett has a famous real-life father. No, not the Doctor Who writer (that’s Stephen Moffat), but actor Peter Davidson. As in… the fifth Doctor.

That is to say, Tennant is marrying not only his on-screen daughter, but also the real-life daughter of his on-screen former self.

We certainly wish the couple all the best. But if they go on to have a daughter, we suggest she might be better off avoiding reruns of a certain sci-fi show to spare them a major identity crisis.