(ABT 1517-ABT 1573)
+---Thomas Trethewy (-ABT 1616)
+---Bartholomew Trethewy
+---Bartholomew Trethewy (-1666)
+---Bartholomew Trethewy
+---Thomas Trethewy (ABT 1675-MAY 1743)
| +---Jane Bruart 
+---Thomas Trethewy (ABT 1710-FEB 1795)
| | +---Phillip Mellow (ABT 1660-JAN 1711)
| +---Joan Mellow (ABT 1680-)
| +---Jane ?
+---Thomas Trethewy (ABT 1735-SEP 1814)
| | +---Richard Jolliffe
| | +---Robert Jolliffe
| | +---Robert Jolliffe (ABT 1546-1602)
| | +---Henry Jolliffe (ABT 1586-)
| | | +---Thomason ?
| | +---Francis Jolliffe (ABT 1622-)
| | | +---Blanch Pearce
| | +---James Jolley (ABT 1682-APR 1754)
| | | +---Rose May
| +---Elizabeth Jolley (ABT 1713-)
| | +---Richard Osborne (-JUN 1667)
| | | +---Eme Varcoe
| | +---Richard Osborne
| | | +---Joan ?
| | +---Richard Osborne (-NOV 1707)
| | | | +---Arthur Michell (-ABT 1657)
| | | +---Constance Michell (ABT 1635-APR 1717)
| | | | +---Thomas Corne (-1647)
| | | +---Blanche Corne
| +---Blanche Osborne
| +---Bettres ?
+---Thomas Trethewy (ABT 1764-)
| +---Wilmot Hicks (ABT 1731-MAR 1816)
+---William Trethewy (ABT 1809-)
| | +---William Penfoun
| | +---Digory Penfoun (ABT 1510-1604)
| | +---John Penfoun (ABT 1530-1561)
| | | | +---John Chammond
| | | +---Jane Chammond
| | +---Digory Penfound (ABT 1562-1641)
| | | | +---Digory de Grenville (ABT 1496-)
| | | +---Honora Grenville (ABT 1531-)
| | +---Arthur Penfound (ABT 1605-)
| | | +---Arminelil Yeo (ABT 1580-)
| | +---John Penfound (04 SEP 1644-)
| | | +---Sibel Nichols
| | +---Arthur Penfound (ABT 1684-)
| | | +---Ann Pollexfen
| | +---Thomas Penfound (ABT 1726-1792)
| | | +---Margaret Anderton
| +---Margery Penfound (ABT 1772-)
| +---Margery Ellet (-MAR 1812)
John Martin Trethewy (01 SEP 1836-)
| +---William Martin (ABT 1791-)
+---Elizabeth Martin (ABT 1816-)
+---Mary ? (ABT 1791-)