(ABT 1737-)
| | +---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)
| +---Elizabeth Trethewy (ABT 1723-)
| +---Grace Rogers (-SEP 1772)
Thomas Trethewy (ABT 1779-)
+---Martha Bennett