Daddy: See those robins, Button?
Button: Yeah! Why are they flying?
Daddy: Because they have wings! Why don't you fly? It's faster!
B: I don't have any wings.
D: Do you think you'll ever have wings?
D: Did you ever have wings?
A: Daddy, I'm not a bird!
I thought it was kind of poignant that even a 3 year old knows that each species produces after its own kind.