3 yo boy potty training

i have been potty training my now 3yo son since january. he gets it right most of the time but he goes through fazes every 2-3 weeks were he suddenly refuses to poo in the potty. He asks me to go, once he sits on the toilet he says there is nothing there, and 2 minutes later he hides in a corner and poos in his pants. He has a twin sister he got it right in 3 weeks and has never had an accident since but it doesnt seem to affect him. We went with 2 months/no accidents and now we are back to pooing in his pants. If you ask him if he wants to go he says no and then goes in his pants. He never had pee accidents, he always asks to pee in the toilet
what do i do?

[AnnieBrooke]

Put him back into pull-ups with little comment, so at least you will not be cleaning his soiled pants.  Potty training shouldn't take nine months, so probably he's just not fully ready.  It doesn't matter whether his sister was, or not.  Read up on the issue on potty training websites or books -- usually a child regresses on the training he has had if there is some change or stress, but in your son's case, he really wasn't fully trained yet.  I've heard a lot of mothers say that once the child was ready, potty training took about 4 days, and they shouldn't have bothered before the child was ready.  

[Kristi74]

Ah, my boy went through the same thing. I talked to my dad (Daddy had three girls then a little boy much later) who commented that boys have different priorities than girls do: girls generally are much more worried about staying clean! They also usually potty train much earlier than boys. My boy's problem ended up being a combination of apathy about the cleanliness (pooing takes longer than going pee and isn't as fun to watch for boys), and constipation! I finally figured out it hurt him sometimes, so he was afraid to try it ANY time! Just some thoughts. If constipation might be part of it, that might be easier to fix than the other: still not sure how to make it move faster for boys. It seems like they just need to decide they're ready, sometimes!