I have 2 cats who are approx 6 years old. I had them by myself for 4 years until I moved in with my wife and her 2 year old son. In the 4 years the cat who is peeing never once went outside the box. About 4 months into the new environment he began going on the dining room and basement floors. I had checked at the vet several times and no health issues. The vet the new environment with all the activity could have caused him aniexty. We recently moved into a new house and my stepson was away with grandparents for a few weeks. The cat in question used the litterbox everyday and never the carpet. Once my stepson came home we began to see pee and poop in the dining room. Is it possible that his presence triggers a negative behavior in the cat?