Captain Peter Sears was born July 29, 1743, in Yarmouth, Massachusetts, the son of Lieutenant Zachariah Sears and his wife, Mehitable Crowell. He married Thankful Howes on January 12, 1769. Childless, they adopted a nephew, Peter Sears (1787-1867), son of Rowland Sears of Ashfield, Massachusetts. The elder Sears worked in the whaling industry before retiring from the sea and running a general store dealing in rum, salt, and other items. In 1789, he served as selectman for Yarmouth. Around 1800, the Sears family moved to Ashfield, Massachusetts, and the elder Peter Sears died there two years later, on July 22, 1802. Young Peter Sears held the rank of lieutenant in the Massachusetts militia for several decades. He married Lucy Fuller in 1808 and left Ashfield in the early 1820s, moving first to Boston and, by 1826, to Dexter, Michigan, where he ran a large and successful farm. The couple had eight sons and two daughters.