It seems that John Wilkes Booth wasn't the only one in the family with Presidential murder on his mind:

Dismissed for 175 years as a fake, a letter threatening the assassination of President Andrew Jackson has been found to be authentic. And, says the director of the Andrew Jackson Papers Project at the University of Tennessee, the writer was none other than Junius Brutus Booth, father of Lincoln assassin John Wilkes Booth.

The Wilkes household must have been a fairly toxic place to grow up...