Both are bad at asking you questions.

Both are suspicious of the postman.

Both are threatened by their own kind.

Both have irrational fears about vacuum cleaning.

Both like dominance games.

Both like to chew wood.

Both mark their territory.

Both take up too much space on the bed.

Both tend to smell riper with age.

Neither does any dishes.

Neither knows how to talk on the telephone.

Neither of them notice when you get your hair cut.

Neither tells you what's bothering them.

Neither understands what you see in cats.