+---Richard Trethewy (ABT 1665-JAN 1741)
+---John Trethewey (ABT 1690-)
| +---Ann Martyn 
(ABT 1666-JUN 1738)
+---John Trethewey (ABT 1720-)
| | +---Phillip Mellow (ABT 1660-JAN 1711)
| +---Temperance Mellow (ABT 1690-MAY 1765)
| +---Jane ?
+---Joseph Trethewy (ABT 1759-)
| | +---Joseph Grose
| +---Jane Grose (ABT 1724-)
| +---Jane ?
+---John Trethewy (ABT 1796-)
| | +---Humphrey Richards (1702-1759)
| | +---Nicholas Richards (ABT 1734-1814)
| | | | +---Amos Bennett
| | | +---Mary Bennett (ABT 1706-)
| | | +---Pascas Richard
| +---Elizabeth Richards (1774-)
| | +---James Trethewy (ABT 1517-ABT 1573)
| | +---Richard Trethewy (BEF 1550-)
| | +---Anthony Trethewy (-JUN 1625)
| | | | +---William Hawkins
| | | +---Joan Hawkins (ABT 1530-)
| | +---Lewis Trethewy (AFT 1619-ABT 1693)
| | | +---Elizabeth ? (-ABT 1644)
| | +---John Trethewy
| | | +---Elizabeth Arundell
| | +---Robert Trethewy (ABT 1698-AUG 1771)
| | | +---Elizabeth ? (-JAN 1708)
| +---Ann Trethewy (ABT 1737-1798)
| +---Grace Rogers (-SEP 1772)
Jane Trethewy (ABT 1827-)
+---Jane Lark (ABT 1801-)
+---Elizabeth ? (ABT 1766-)