Why do people from Boston hate New Yorkers and why do they hate us?

Im a Bostonian and I love Boston and for some reason me and all my friends and family hate New York even people I don't know that live in Boston say they hate New York and don't get me wrong I have friends that are from New York and they even say they hate Bostonians so Im wondering why it seems if your from Boston your suppost to hate New yorkers and why they hate Bostonians?