Do all youth think they are the non favorite child??

I have 3 sons aged 19-25. No one is the favorite, the favorite is the cat and the dog anyway they all have their various completely different personalities. They all take turns stating who is the favorite. Doesn’t matter how often I state no favorites here! The middle thinks most hard done by, so moved states. We still get along. The eldest is convinced the youngest got more love growing up and the youngest feels it’s the eldest. Does my head in. Is this typical?