Why is my 10-year-old soiling his pants?

[YoungMommy31]

My 10-year-old stepson is soiling his pants and I don't know why. I have two stepsons, 13 and 10-years-old and a 16-month-old baby boy of my own. He is and has been potty trained for AWHILE now and, he picks and chooses when he wants to soil his pants. It isn't a DAILY occurence but it does happen (bimonthly usually and sometimes nothing for 6 months at a time), and those are the times that we KNOW OF. It's frustrating because we have TRIED everything. His father and I have tried putting him on a toilet schedule, we have used diapers (he won't soil his pants when wearing diapers but the VERY next day after not having to wear them anymore, he does it yet again), using a reward system, a talking-to, grounding and spanking. And it ALL WORKS for awhile though and then, he's back to his old ways. And it's not because of me either - I know after all I am the EVIL STEPMOTHER, it must be MY FAULT but he's been doing this WAY before I ever came into the picture. I've been with his father since he was 6-years-old and he's been consistently soiling his pants ever since then and, really since being potty trained. When it does happen, it's usually when he's playing and his father and I think he's too LAZY to stop playing to find a restroom - now he's been holding it for too long and has no choice but to soil his pants.  He doesn't only go #2 on himself but he also urinates on himself, it's less often though. He always lies about it too (for fear of getting into trouble) but seems unfazed when confronted with it. No guilt or shame. We make him wash his own underwear and, it doesn't matter - he's not grossed out AT ALL by it. Because this has gone on for 3 and a half years now. He gets into trouble at school too, usually for being a chatterbox and being out of his seat but also for inappropriate language (sexual), cursing, destruction of school property, etc. So, what do WE do? Any advice? Or is there anything that we can do?

[Sandman2]

   If it is only happening about twice a month and sometimes not for a long period of time, I doubt that it is encopresis.  
   If it happens when he is at school, it is not uncommon for younger kids to be afraid to use the bathrooms.  Many times letting the teacher know this might be a problem and to make sure that he can use the bathroom when he needs to and not have to use it during recess or lunch when the older kids are around can solve this problem.  However, I would also stay in close contact with his new teacher.  It sounds like he has had a lot of problems at school and you need to figure out what is going on.
   But, because you also mentioned other problems at school, I wonder if anybody has ever mentioned the possibility of ADHD.  He does have some of the symptoms (including his potty problems).  Of course he is the youngest child with two older brothers, so he probably is on the short end of the stick with them.  And now with the new little bro, he probably does not get a lot of attention at home - which can lead to other problems.   And, if this has been going on for 3.5 years - I wonder when his original mom began to disappear from his life?  Anyway,  there is a good chance that he could use some more attention, but I also would take a look at this link on ADHD - http://www.help4adhd.org/en/about/what/WWK1
   Hope this helps.

[RockRose]

Google encopresis.

It sounds like he needs more fiber.  I know you can say he's clearly doing this on purpose,  but I don't think so.  I think he likely has encopresis and would benefit from a lot of extra added fiber to his morning cereal,  or metamucil.