Of course, parents never say they have favorite but they sure do.
The moment a parent says 'why aren't you more like...' you know there is a favorite. They are treated differently; nicely. My father always takes my older sisters opinion on everything and treats her much better. He used to make me clean her room when she was in high school and while she was in community college as well. He would tell me she had no time because she was studying, total BS! She always got whatever she wanted whenever she wanted it. I, on the other hand, was dealt with much more stringently. It happens can't really change anything.
Sorrow found me when I was young
Sorrow waited, sorrow won
Sorrow they put me on the pill
It's in my honey, it's in my milk