I’ve been thinking a lot this week about Darwinian imperatives and the function of DNA. No, not because I’m taking an evening class in advanced reproduction, but because I’ve just found out that my ex-wife is pregnant.

She told me when I dropped off the kids at hers. Her new partner, Gary, was in the kitchen fixing me something revitalising in case I went into a faint, like a woman from an Elizabethan drama who is prone to a touch of the vapours. Actually, my immediate reaction to the news, after bursting into a verse or two of In Dulce Jubilo and low-fiving my eight-year-old son, was a ridiculously irrational, “Gulp! But what if it’s mine?”

Now, I failed my Biology ‘O’ Level (that’s the code-phrase for GCSE to readers under 35), so I think I can be forgiven for this, but I did wonder for a brief moment whether a stray cell of mine may have, you know, demonstrated a feat of endurance comparable to Moses on the mountain and done something lewd and lascivious with a particle of genetic material belonging to the former Mrs L (and sincere apologies to our more sensitive readers for the graphic and biblical nature of that sentence, by the way).

A quick leaf through some periodicals on the subject of procreation and natural science at my local Borders soon set me straight — it’s amazing what you can learn from a copy of FHM these days.

Joking aside, this startling event does beg some serious questions. Like, presuming it wasn’t an immaculate conception, how do we deal with the whole sex-before-marriage issue with our children? Does Gary have the brass cojones to test the theory that Jewish women don’t believe in sex after marriage? Should I be thinking about having another baby myself? And if so, will it matter that I don’t have a girlfriend?

At my age, I’m more likely to meet someone with children of their own. “Blended families”, they call them. I don’t tend to blend. I’m more of a frictional coalition man, or a proponent of the tense alliance. Still, a Jewish version of The Brady Bunch quite appeals, as long as I don’t have to have a curly perm like Mike Brady or put up with a basket-case like Marcia — there’s only room for one fragile narcissist in my house.

Karen, my ex-girlfriend from 1992-3 (I have a mental chronology of all my erstwhile other-halves – Julie 1981-4, Claire 1985-8, Eleanor 1988-90, etc. Hmmm, must make a wall-chart at some stage), who has two kids of her own, recently suggested we move in together, but last I recall she had an eating disorder and an obsession with moisturising lotion – or was it a lotion disorder and an obsession with moisture? I can never recall. She wasn’t technically Jewish although she did live at the time a street away from Stonegrove shul and regularly went to Edgware Maccabi as a sort of honorary Red Sea pedestrian. Come on, she’s a mikveh away from the real thing.