Recently on one of the exotic pet forums, there was a discussion about how to teach foxes to tolerate children, and Gizmo and I were mentioned in it a few times. One of the members on the forum, who shall remain nameless in this post, said that he lets his niece carry his baby fennec around like a doll and dress it up, on the theory that if she's subjected to it as a pup, she will put up with it as an adult. I just want to go on the record as saying I don't approve of that method of teaching any exotic pet tolerance of children; it's too easy for things to go wrong, and a bite won't end well for anyone involved.
I figured that it'd be best to make it clear what I did to make Gizmo like kids, and what my thoughts are on the matter.
I have rules for Gizmo around people (one of these rules is he is ONLY allowed to roughhouse with me and my mom), and yes, Gizmo has been socialized to children and is good with them. However, Gizmo is never pinched, pulled on, dragged around, or otherwise manhandled by children. I simply won't allow such treatment. Gizmo is also never left unsupervised around children for both his sake and theirs.
After teaching Gizmo how to take treats nicely, and he was doing it reliably, I had children who I could trust to behave and knew VERY well (my little cousins) feed him treats, talk to him softly, pet him, etc. He was exposed to kind, quiet, gentle children at a young age, and learned to associate kids with affection and good things.
Gizmo has never had a negative experience with any child.
Back before the whole mess with the county, children in the neighborhood were allowed to pet him and rub his belly, but only after I made it very clear to them what is acceptable behavior on their part and what is not. And the contact was entirely on Gizmo's terms. I've never seen him not eager to greet a child (as all of his experiences with them have been positive), but if Gizmo ever seemed wary or unsure of ANYONE, the contact ended there, and he was never made to endure being touched by someone he didn't want touching him.
Now, at home when I'm playing with him, sometimes I do stuff that annoys him. I tug on his ears, roll him off his feet, hold him down, and am irritating in general. I don't do this every play session, but I make sure to really annoy him during play at least once a week. This is to see how he handles someone being "unfair", and to offer a quick correction if he reacts badly.
Overall, he's very tolerant of me being "bad"; his first response is to get whiny, his next response is generally to go under his play cube and refuse to come out. I reward these behaviors, as I think that avoidance is the best response he could possibly have towards rough treatment. However, under no circumstances would I allow anyone to treat him roughly.
When it comes to animals and children, it's far more important to teach a kid how to treat animals properly, not to teach an animal to put up with harassment and abuse. Animals don't think "human", so you have to teach a child to understand how the animal thinks.