+---Richard Trethewy (ABT 1665-JAN 1741)
+---Richard Trethewy (ABT 1700-ABT 1764)
| +---Ann Martyn 
(ABT 1666-JUN 1738)
+---Richard Trethewy (ABT 1728-21 APR 1818)
| | +---Humphrey Harris
| | +---Gilbert Harris (ABT 1637-)
| | +---Gilbert Harris (ABT 1665-)
| | | | +---Richard Wills
| | | +---Jenifer Wills (ABT 1632-)
| | | +---Christian Best
| +---Jenifer Harris (ABT 1696-1780)
| | +---Thomas Hockin (-ABT 1607)
| | +---John Hockin
| | | +---Elizabeth ?
| | +---John Hockin
| | +---John Hockin (ABT 1616-DEC 1696)
| +---Elizabeth Hockin (ABT 1658-)
| +---Blanche ? (-ABT 1699)
+---Richard Trethewey (ABT 1756-DEC 1818)
| | +---David Warne
| | +---John Warne (ABT 1656-)
| | | | +---Henry Arthur
| | | | +---Gregory Arthur (ABT 1599-)
| | | +---Honor Arthur (ABT 1632-)
| | +---John Warne (ABT 1700-)
| | | | +---Richard Rounsevall
| | | | +---Gregory Rounsevall (ABT 1617-)
| | | | | +---Jane ?
| | | +---Jane Rounsevall (ABT 1664-)
| | | +---Mary Olver
| +---Mary Warne (ABT 1730-30 MAY 1786)
| | +---Johannes Doketon
| | +---John Doketon (BEF 1459-)
| | +---Thomas Doketon (BEF 1490-)
| | +---Richard Docton (-JAN 1571)
| | | +---Alicia Ash (BEF 1490-)
| | +---Thomas Docton (-AUG 1638)
| | | +---Thomasin Saunder
| | +---John Docton (ABT 1600-JUN 1650)
| | | +---Susanna (Susan) Babacom (-DEC 1634)
| | +---John Docton (ABT 1636-)
| | | | +---John Arundell of Lanherne
| | | | +---Thomas Arundell of Lanherne
| | | | | | +---Gerald Danet
| | | | | +---Elizabeth Danet
| | | | +---Thomas Arundell (-AFT 1620)
| | | | | +---Elizabeth Trengove of Nance
| | | +---Cecilia Arundell (-MAR 1639)
| | | +---Rachell Monp'son
| +---Honor Docton (ABT 1700-)
| | +---Thomas Tregeare
| | +---Henry Tregeare (ABT 1609-)
| +---Mary Tregeare (ABT 1655-)
| +---Mary ?
+---Richard Trethewey (21 NOV 1779-09 NOV 1845)
| | +---William Varcoe
| +---Elizabeth Varcoe (ABT 1753-)
| +---Susanna Triverton
+---Richard Trethewey (17 DEC 1805-25 JUL 1886)
| | +---William Lemin
| +---Alice Lemin (ABT 1786-DEC 1865)
| +---Alice ?
+---James Trethewey (03 SEP 1847-21 APR 1917)
| +---Mary (Peggy) Matthews (ABT 1816-)
+---Horace George Trethewey (08 FEB 1884-11 JAN 1966)
| +---Augusta James (02 NOV 1849-19 JUL 1919)
+---James Gibson Trethewey (12 MAY 1910-19 APR 2000)
| +---Margaret May Gibson (14 MAY 1885-10 MAY 1982)
Leonard James Trethewey (19 MAR 1944-)
+---Enid Clista Dunn (23 JUN 1916-07 JAN 1986)