talesin, I think that my cat definatly started to change his attitude around the time that my first son was born. We had two at the time and they were littermates. One cat was like my wifes baby untill the real deal came along. Then he started to mark his territory. Here, there, every where, and any where. This cat even pissed on my bed while my wife and I were sleeping in it.
The straw that broke the camel's back was when I bought a brand new queen size bed, sheets, matress, and comforter After spending every spare cent I had on these items the cat decides to piss all over them. When I discovered what he had done I got rid of him. I couldnt take him any more.
His litter mate was cool though. He was a good cat and I did enjoy him untill he ran away.
My cats too couldn't refrain from eating the home grown. I put a milk crate over them to prevent them from destroying the plant prematurely.