The best time to talk to your nine-year-old boy about women’s plumbing and these sorts of sexually delicate territories is when he’s asleep.

This is what every trying father discovers after said boy lays splayed on the living room floor pretending he’s having a baby.

Yes, my son Jon was in obvious pain – it seems no epidural was provided during his birthing ordeal – and so his big show was made all the bigger and louder to, naturally, make fun of his sisters.

Hannah had just said that she wasn’t looking forward to this part of motherhood’s official start. (But 29, says Hannah, is the best age to marry.)

And in line with a growing trend to not marry, (not that there’s anything wrong with singleness), Liz said she wasn’t sure she wants to marry at all. She will simply adopt a gaggle of kids and go it alone with them. Well …

That’s when Jon went to the floor in his great and mocking agony.

Of course these sort of, uh, discussions on birth and boobs and such are nothing new in this family.

In this case it was precipitated by the news that Mary Ingalls and her fiancé – they got engaged at just 13 – weren’t exactly sure what the future would hold after the young, farming lad, a poet, got a four-year scholarship to go off to university and pursue his writing.

It was a rather worthwhile episode (my kids are big fans of Little House on the Prairie just like The Waltons, another great sex-talk primer) because it opened all sorts of discussion on the importance of not only women’s plumbing, or just how young a mother from the 19th century might be, but also this other tricky area of letting go of the people you love.

It also opened discussion about our wiring, that is how you and I and Mary Ingalls and my son Jon and the guy down in Apartment 8 are all made different enough that we can each contribute our own God-given talents while on this spinning ball, each with our own unique gift to share, each respecting the other.

Even if this respect means letting go of your dreams, and your love, while the train pulls away with him onboard, and your heart too. Poor Mary.

“But Dad,” Jon said. “Mary’s not old enough to have kids. You have to be 20!”

“Well,” I said.

And then, after Jon was in his room, half asleep, I explained it all. Everything. Mostly. Well, some.

He grunted a grunt that told me either he had understood, or maybe he didn’t (hey, it’s rather complicated even for The Old Man), but I had done my duty and now I could now leave him to dream whatever young boys may.