(ABT 1832-)
Thomas Dean (ABT 1868-)
| +---James Trethewy (ABT 1517-ABT 1573)
| +---Thomas Trethewy (-ABT 1616)
| +---Bartholomew Trethewy
| +---Bartholomew Trethewy (-1666)
| +---Bartholomew Trethewy
| +---Thomas Trethewy (ABT 1675-MAY 1743)
| | +---Jane Bruart 
| +---William Trethewy (ABT 1712-JAN 1777)
| | | +---Phillip Mellow (ABT 1660-JAN 1711)
| | +---Joan Mellow (ABT 1680-)
| | +---Jane ?
| +---John Trethewy (ABT 1741-)
| | +---Grace Rickard
| +---Richard Trethewy (ABT 1774-)
| | | +---Francis Honey
| | +---Elizabeth Honey (ABT 1742-)
| | +---Ann Johns
| +---William Trethewy (ABT 1814-)
| | | +---Alexander Bone
| | +---Rebecca Bone (ABT 1777-)
| | +---Rebecca Boney
+---Jane Trethewy (ABT 1838-16 APR 1870)
| +---Nicholas Williams
+---Martha Williams (ABT 1809-BEF 1890)
+---Frances ?