Ah, great catch. I keep forgetting about sexual reproduction. To correct the point while keeping the math easy, make it 8 kids each, half of whom have 8 kids an

Ah, great catch. I keep forgetting about sexual reproduction. To correct the point while keeping the math easy, make it 8 kids each, half of whom have 8 kids and half none, etc. Then each couple contributes on average to two couples in the next generation, etc.