+---Richard Trethewy (ABT 1665-JAN 1741)
+---John Trethewey (ABT 1690-)
| +---Ann Martyn 
(ABT 1666-JUN 1738)
+---Joseph Trethewy (ABT 1735-DEC 1816)
| | +---Phillip Mellow (ABT 1660-JAN 1711)
| +---Temperance Mellow (ABT 1690-MAY 1765)
| +---Jane ?
+---John Trethewey (ABT 1764-JAN 1834)
| | +---John Rickard
| | +---Jonas Rickard (ABT 1705-)
| +---Caroline Rickard (ABT 1734-)
| +---Honour ?
+---Benjamin Trethewey (ABT 1802-BEF 1861)
| +---Charity Strangeman (1756-)
+---Richard Trethewey (19 NOV 1829-18 APR 1897)
| | +---Richard Thomas (ABT 1763-)
| +---Elizabeth Thomas (ABT 1808-)
| +---Mary ?
+---Jabez John Warne Trethewey (07 SEP 1864-1935)
| | +---John Warne
| +---Naomi Warne (ABT 1834-1912)
| +---Mary ?
Eileen Marguerite Trethewey (11 APR 1912-)
+---Margaret (Maggie) Ellen Wright (07 DEC 1873-19 OCT 1950)