(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 ?
+---Richard Trethewy (ABT 1753-MAR 1836)
| +---Grace Rickard
+---Thomas Trethewy (ABT 1797-)
| | +---John Cundy
| | +---Solomon Cundy (ABT 1690-DEC 1759)
| | +---William Cundy (ABT 1733-)
| | | | +---David Pearce
| | | | +---Isaack Pearce (ABT 1666-)
| | | | | +---Alice ?
| | | +---Alice Pearce (ABT 1698-NOV 1739)
| | | +---Alice ?
| +---Susanna Cundy (ABT 1761-)
| +---Jane Treneman (ABT 1737-ABT 1809)
+---Joseph Trethewy (ABT 1839-19 MAY 1915)
| +---Mary Maneer (ABT 1803-BEF 1871)
Thomas Henry Trethewy (22 DEC 1881-14 FEB 1942)
+---Elizabeth Hockin (ABT 1840-07 MAR 1915)