My daughter has a pet fox... Is it dangerous?
Solution 1:
After reading the wiki entry on pets:
Fox pets (well ANY pet they might drag home) are completely harmless. They won't attack unless provoked.
Solution 2:
The premise is incorrect.
Children are set to essential by default. This makes them effectively invulnerable.
On top of that, they don't even take damage.
Unless you went around and modified your kids via the console, they can't even be hurt to begin with.
There's a reason why someone else asked "How do you kill children?"