How Bad Would Another Kid Be?

new kid difficulty functionOccasionally people ask us what it’s like to go from n to n + 1 kids. The occasion is a couple, with one fewer kid than us, considering having another, which they’re afraid may be impractical and illogical, maybe even irresponsible. The simple answer is, it’s not as bad as going from n – 1 to n.

Mathematically, the more kids you have the easier it is to increment because you’re adding a difficulty factor of 1/n. From 0 to 1 you’re increasing by an impossible, infinite amount, 1/0; from 1 to 2, by 100%; from 2 to 3, by 50%; etc. So number 1 is a dramatic shock, but the proportional increase gets smaller the more you add.

That’s what people like to hear. It makes sense, and it sounds feasible. Keep in mind, the main assumption of this model is that your next kid will be of similar difficulty. Instead, kids usually differ in temperament, where one is an angel and the next is their alter ego or, worse, their arch nemesis. Just when you’ve got things under control with n kids, changing diapers one-handed, the nth + 1 shows up and you’re changing diapers no-handed. Chaos. Anarchy. Then you figure it out again. Then you have to potty train, again.

So, overall, in the long run, on average, the next kid is easier than the last. If you can make it to n = 6 you’ll hardly notice the change.