(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 ?
+---Robert Trethewy (ABT 1759-ABT 1786)
| | +---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 ?
Grace Trethewy (ABT 1786-)
| +---Abraham Grigg
| +---William Grigg (ABT 1728-)
| | +---Joyce Phillips
+---Grace Grigg (ABT 1755-)
| +---William Varcoe (ABT 1586-1639)
| +---William Coad Varcoe (ABT 1639-)
| | +---Temperance ? (ABT 1603-1645)
| +---John Varcoe (ABT 1685-MAR 1764)
| | +---Mary Edwards (ABT 1661-)
+---Grace Varcoe (ABT 1727-)
+---Mary Yelland (-NOV 1764)