Sam is four and a half ... and a very bright four and a half, if I do say so myself ... so has developed keen observation skills and prodigious curiosity. Like good old Carnac the Magnificent he often knows and sees all.

Unlike many kids who've been adopted into families where the parents are young and pre-menopausal, Sam hasn't been exposed to pregnant friends of Mom and Dad, and the excitement, hoopla and conversation that goes with the process of making a baby from scratch.

To the contrary, in his experience babies come from Cambodia. In addition to his sister, the other three babies he's had contact with have all come from Cambodia, and as far as I can tell, he's never given a moment to wondering about this. Apparently, it makes total sense, so the answer to the question, "Where do babies come from?" is an easy one for him.

With my assistant, Catherina, expecting her baby within the next couple of weeks, I thought it a good idea to begin prepping him for this new arrival. Since she lives in our guesthouse and has little relationship with her mother or family, we'll be interacting a lot even through her maternity leave, and I'll be helping with the baby most days. Getting my kids ready for this additional demand on my time, and the new little person around the house, is all part of how our family set-up works … we’re one happy clan down here in our valley in the forest.

As you can see from the photo, there's no mistaking Catherina's condition ... or so I thought.

Nodding and showing complete comprehension when we've discussed the impending birth, I made some pretty silly assumptions for the mother of a four-and-a-half-year-old who has done this before.

Turns out, Sam has been waiting for Catherina to get on a plane headed for Cambodia. The thought that there would be any other way for a baby to come along had not entered his mind.

A bit of bird-ing and bee-ing was employed to get points across, and without going into age-inappropriate territory I managed to convey the broad strokes of human reproduction. Although surprised to learn this alternate family-building method, he accepted the information, then moved along immediately to drawing pictures of dinosaurs.

A bit puzzled, I asked if he hadn't noticed Catherina's tummy getting bigger and been curious about it.

"Nope," he said. "Not really. She looks just like Dad."