I don't know what to do. We have been trying to get our son to poop in the toilet since he was 3. He is now 5 and shows no signs of starting any time ever. He has done it once or twice but he poops in his underwear almost daily. I have tried asking him about it in every way that I can and i never seem to get anything more than "I don't know" as to why he didn't go to the toilet. (He can pee no problem)
We have tried rewards, sitting him there regularly etc nothing works.
Update a bunch of months later:
My wife and I are now at the end of our ropes. He still does not poop on the toilet. We have a rule that we give them a shower when they poop themselves (so we can get them clean) And when I just showered him I asked him why he can't poop on the toilet. He was unable to respond to me, its like he forgot how to talk.
We have tried bribing him with toys, making him sit on the toilet, they are working with him at school (or so I understand) and so far NOTHING works. He has pooped on the toilet twice in the last year.
And now his younger brother is doing the same. He actually was using the toilet for a while, but now is back to pooping his pants.
Update, Even more months later
It has now been something like 2 1/2 years and he is still not pooping on the toilet. Its not that he has accidents sometimes its that he poops his underpants EVERY day. As far as I can tell he makes no sign of having to go and has no clue that he is about too.
He goes to a special needs school (He is somewhat autistic) and they have been working with him but still nothing. We have tried offering him stickers or candy for pooping on the toilet.
Update: Dec 2012
At this point I am at a loss, we have taken him to the Doctor and as far as we can tell there is nothing physically wrong. And the doctor has no idea of what to do.
At this point he won't even sit on the toilet, if you try to get him to sit (never mind actually poop) he will scream bloody murder.