The Salt Lake Tribune has turned up plenty of polygamists in Mitt Romney's family history, but the Massachusetts governor insists that marriage is between a man and a woman—not between a man and seventeen women.
Romney's great-great grandfather on his paternal grandmother's side is a famous Mormon from the settling of the western realm of Deseret (part of which later became Utah), where followers fled in the 1800s to escape anti-Mormon persecution fueled, in part, by opposition to polygamy.... thus proving that polygamy can be fatal.
Parley P. Pratt was one of the influential LDS Church leaders during the early years. He married 12 times, though his first wife died before he took a second. A former husband of one of his plural wives eventually killed Pratt. [Link]