(-JUL 1733)
+---Richard Trethewy (ABT 1720-)
| +---Isabel Beaubery 
(-FEB 1732)
+---Philip Trethewy (ABT 1765-)
| +---Ann Jewell
+---Robert Varcoe Trethewy (ABT 1804-)
| | +---Robert Varcoe
| +---Grace Varcoe (ABT 1774-)
| +---Joan Benny
+---Richard Trethewy (ABT 1833-30 MAY 1893)
| +---Ann Guard
+---Phillip Trethewy (14 JAN 1877-)
| +---Priscilla Parsons (22 DEC 1844-14 NOV 1911)
+---James Ernest Trethewy (ABT 1909-SEP 1993)
| +---Katherine (Kate) Phillips
Robert Trethewy
+---Gladys V Weldon (05 AUG 1915-25 MAR 1994)