(ABT 1517-ABT 1573)
+---Thomas Trethewy (-ABT 1616)
+---Bartholomew Trethewy
+---Bartholomew Trethewy (-1666)
+---Thomas Trethewey (-ABT 1692)
+---Bartholomew Trethewy (ABT 1667-MAY 1755)
+---Walter Trethewy (ABT 1702-NOV 1751)
| | +---Robert Trethewey (-JUL 1676)
| | +---Walter Trethewey (-1710)
| +---Elizabeth Trethewey 
(ABT 1670-AUG 1743)
| +---Mary Brewer
+---Humphrey Betty Trethewey (ABT 1731-JUL 1769)
| +---Joan Woon (-1735)
+---Thomas Trethewey (ABT 1758-25 FEB 1812)
| | +---Richard Hendra
| +---Blanche Hendra (ABT 1734-JAN 1775)
| +---Jane Murton
Humphrey Beattie Trethewey (ABT 1801-24 MAY 1864)
+---Elizabeth Carvolth