I was raised in a kosher household. Though I never fully understood why I couldn't eat cheeseburgers or pepperoni pizza—the theology still confuses me—I quickly learned to follow the rules. At birthday parties, I always informed the hosts that I preferred my pizza plain. If they forgot, I would just eat the crust.

What's odd about such self-restraint is that I was terrible at holding back my childish desires in almost every other way. Even as I skipped the pepperoni, I would...