Some of the replies didn't seem to be very helpful. That being said, I have to agree that it's hard to advise you without more information. Fencing is a terrific sport and I strongly recommend it for kids. More than any other activity, it teaches them good sportsmanship. It teaches them to be good losers, but more importantly, it teaches them to be gracious winners.
Read the rest of the threads on the parent's page and it will give you a better picture.
For me, the first year was difficult as a parent, as it takes about that long to really figure out what is going on. It started out with my son fencing, then he got me to do it, and now my daughter also fences.
It's true that fencing is not for everyone, and if your kids don't want to fence then let them out. If they do want to, give it at least a year and see how it works out.