Isaac Lathrop, Jr. was born 13 February 1707 in Plymouth, Plymouth County, Massachusetts, United States to Isaac Lathrop (1673-1743) and Elizabeth Barnes (1677-1757) and died 26 April 1750 Plymouth, Plymouth County, Massachusetts, United States of unspecified causes. He married Hannah Freeman (1709-1730) 27 November 1729 in Harwich, Barnstable County, Massachusetts, United States. He married Priscilla Thomas (1709-1796) 29 January 1732 in Plymouth, Plymouth County, Massachusetts, United States.
Children
| Name | Birth | Death | Joined with |
| Freeman Lathrop (1730-1731) | |||
| Name | Birth | Death | Joined with |
| John Lathrop (1733-) | |||
| Isaac Lathrop (1736-1808) | |||
| Nathaniel Lathrop (1737-1828) | |||
| Thomas Lathrop (1739-1794) | |||
| Caleb Lathrop (1742-1766) | |||
| Priscilla Lathrop (1747-1810) | |||
Siblings
| Name | Birth | Death | Joined with |
| Melatiah Lathrop (1701-1771) | 29 June 1701 Plymouth, Barnstable County, Massachusetts, United States | 6 July 1771 Plymouth, Barnstable County, Massachusetts, United States | |
| Elizabeth Lathrop (1705-1745) | 15 April 1705 Barnstable County, Massachusetts | 1 November 1745 Plymouth, Plymouth County, Massachusetts | Samuel Bartlett (1696-1759) |
| Isaac Lathrop (1707-1750) | 13 February 1707 Plymouth, Plymouth County, Massachusetts, United States | 26 April 1750 Plymouth, Plymouth County, Massachusetts, United States | Hannah Freeman (1709-1730) Priscilla Thomas (1709-1796) |