Just my ideas. It might be better to raise children as Buddhists.
Important to tread lightly (and wisely) though; my mentor is a perfect example of this. His son is now in his late 20's, but when he was a child, my mentor made sure that he created a fun environment around the dharma. He never pushed it on his son, but made it enjoyable. For instance; he would place his son on his shoulders and let him ring the bell and wave the vajra around and they would clap and dance and sing Vajra Guru Mantra... his son remembers it to this day.
When his son got older, and there were teachings to attend, my mentor would set up a fun outing around the event, and let his son bring a video game he could play quietly during the teaching. Before hand they would go and get lunch wherever his son wanted to, and afterwards they would go see a movie and get ice cream. So his son learned that going to the teachings wasn't all that bad. During empowerments and important transmissions (meaning in the moments the teacher was giving the wang or lung) he would have his son sit on his lap and pay attention, but the rest of the time he was allowed to play quietly. He never pushed it on his son though, and now that his son is older, he's an avid Chödpa and is very passionate about the Dharma. He's also a happy and well balanced guy, so my mentor did good raising him.
I do the same with my son, who's 4. He knows about buddhas, and says they're like magical ninjas, he'll have his toy ninjas pretend to meditate etc. I let him ring the bell and pretend he's shooting lighting out of the vajra. We hung prayer flags in his room, and he's visited my Kagyu lama here in SF who gave him a small wooden prayer wheel and a pouch for his toys. I've taken him to group practice (ganapuja) and let him take a brief look at webcasts from Namkhai Norbu Rinpoche (when I'm watching) until he loses interest. He knows about the Dzogchen guardians (I have a large thangka with the three of them on it he looks at) and says they're the guys who kick butt. He has a positive perception of the Dharma and that's all that's important I think. Whether he chooses to be involved with it when he's older, that will be up to him, I'll never push it on him. The last thing I'd want is to try and condition him like that. That is when you get resistance and can ruin the experience for them. It's just good to create a positive and light environment with the teachings, have the Dharma present and accessible but don't ever indoctrinate or insist upon it.