Mine did!!! He was totally house trained and when he started lifting his leg at about 14 months, he started peeing in the house again. This is really bad, but one time he actually lifted his leg on my 2 year old son!!! It took about a month, but he learned not to lift his leg in the house. I think what actually started him doing it was we had a female in heat in the house and it seemed everywhere he smelled her, he had to mark it. So...if yours never learns to lift his leg, think of it as a good thing!