Forgetfulness: Irresponsible or Normal

Question:

My question is how responsible can I legitimately expect my 10 yr old stepson to be. I believe he “forgets” to do chores right or brush his teeth etc. because he gets special undivided attention when he is getting in trouble even though it is negative attention. He is a very intelligent boy and has no mental challenges whatsoever. We have issues every single day of him “forgetting” to do everything. He refuses to take any responsibility or accountability for his actions. His regular response is…”uh I forgot”. We have tried the special time for him, giving him less responsibility, grounding him, taking his things away etc. My biggest concern is I worry that he may be getting disciplined for things he isn’t capable of doing at his age. Should he be able to remember to brush his teeth, make his bed when he cleans the room, put a trash bag in the garbage after it is dumped? These problems occur every single day over and over no matter how many times he is told. These issues are frustrating me so much that I am not being the mother I am capable of being to any of my kids because I am always upset or dealing with this issue. P.S. just to prove I think it is all on purpose he is on the citizenship honor roll at school for his exceptional RESPONSIBILITY! I try not to get upset but it’s been going on for so long.