(ABT 1836-)
Hannah Searle 
| +---Philip Trethewy (-JUL 1733)
| +---Richard Trethewy (ABT 1720-)
| | +---Isabel Beaubery (-FEB 1732)
| +---Robert Trethewy (ABT 1759-)
| | +---Ann Jewell
| +---Robert Trethewy (ABT 1802-BEF 1861)
| | +---Elizabeth Sarah
+---Elizabeth Trethewy (ABT 1839-1902)
| +---William Trevithick
+---Mary Ann Trevithick (ABT 1808-1877)
+---Elizabeth Harry