(18 JUL 1992-)
| +---James Trethewy
| +---Richard Trethewy (ABT 1665-JAN 1741)
| +---William Trethewy (ABT 1694-)
| | +---Ann Martyn 
(ABT 1666-JUN 1738)
| +---James Trethewy (ABT 1719-)
| | +---Jenefer Sweet (-SEP 1733)
| +---William Trethewy (ABT 1753-)
| | +---Grace Warne
| +---Richard Trethewy (02 FEB 1799-24 DEC 1875)
| | +---Catherine Scholier
| +---John Trethewy (25 JUL 1823-24 SEP 1876)
| | +---Catherine Hooper (25 MAR 1796-06 DEC 1893)
| +---Arthur James Trethewy (08 MAY 1855-26 SEP 1923)
| | +---Margaret Eleanor Ross
| +---Robert Parker Trethewy (29 DEC 1909-14 FEB 1981)
| | +---Mary Alberta Parker (20 FEB 1871-14 APR 1961)
| +---Robert Parker Trethewy (07 JAN 1948-)
| | +---Lavon Rae Wohlgemuth (31 MAY 1924-)
+---Elizabeth Alberta Mae Trethewy (23 MAY 1972-)
+---Barbara Stokes (08 MAY 1947-)