According to Weis, Thomas was a 5th cousin to Henry Josselyn (b. 1606, d. bef 10 May 1683), and John Josselyn (b. 1608, d. aft 1675), both of whom settled in Black Point, Maine. These two were, in turn, descendants of Sir Thomas Josselyn (1507-1562), of Hide Hall, Sawbridgeworth, Hertfordshire.