When you love them like your own kids (at least for me, since I don't have human kids) and tell others that they are your kids.
When you call them by name and your family gets confused -- "Whos' that?!"
When you kiss them goodnight.
When you fill up your camera with pictures of them.
When you can tell what breed that random chicken online (or at the fair, shelter, etc.) is without being told.
When you can differentiate who's who when blindfolded, just by their voices.
When you'd rather spend time in the coop/run/yard with your chickens than watching TV.
I could think of more, but I'm being called away by farm duty.
I love all the posts on this thread! I can relate to almost all of them. (Does that mean....
I'm addicted to chickens?! )