 He was the son of Mayflower Pilgrim Isaac Allerton Sr. and his second wife Fear Brewster, the daughter of Elder William Brewster, the Pilgrim colonist leader and spiritual elder of the Plymouth Colony, and passenger aboard the Mayflower and one of the signers of the Mayflower Compact; and Mary Brewster.Fear arrived at Plymouth, Massachusetts on July 10, 1623 aboard the Anne.Fear died sometime before December 12, 1634.