Since the days of Cain and Abel, sibling rivalries have dotted history in many shapes and forms.
Some siblings sue each other over money or defamation while others live out their days amid a frigid silent treatment. Some sibling rivalries are purely playful, competitive one-upmanship.
These sibling groups not only prove that it's impossible to expect brothers and sisters to get along all the time, but they also show that some siblings simply have it out for one another.
Here are 18 of the most epic sibling rivalries of all time.
Melissa Stanger contributed to an earlier version of this article.