Probably yes, but it also depends on how talented your kid is.
But chances are that she probably won't be 6-year-old Lopez Lomong running in the African wilderness for 3 days straight.
So use Galloway's run and walk method, and make sure your child is well hydrated and stops to refuel. The goal should be to finish rather than to race.
My friend's 9-year-old son runs along with his dad in 10k races all the time. He's now faster than his dad.