Most parents around here cycle with their children. You must be a confident and strong cyclist first though as when the seat goes on the back it alters your balance and makes control of the bike harder. This gets harder as they get heavier, obviously.
But I don't want to put you off. Some of my friends find it easier with the seat that goes on the crossbar, (between the saddle and the handlebars.) I think this is less safe though as the seat 'shell' is a lot smaller. DH really rates the co pilot and did his research. At the time we bought ours it was the safest.
And, obviously, helmets! Happy cycling.