(ABT 1777-)
+---Henry Roberts (ABT 1805-)
| +---Elizabeth Brokenshire 
Mary Roberts (ABT 1832-)
| +---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
| +---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 ?
| +---John Trethewy (ABT 1780-BEF 1861)
| | +---Wilmot Hicks (ABT 1731-MAR 1816)
+---Mary Trethewy (ABT 1808-)
| +---John Snell
| +---Henry Snell (ABT 1700-ABT 1770)
| | +---Joan Kent
| +---Henry Snell (ABT 1739-)
| | | +---John Best (ABT 1648-AFT 1696)
| | | +---John Best (ABT 1683-)
| | | | +---Grace John
| | +---Grace Best (ABT 1713-01 DEC 1799)
| | | +---Robert Phillips
| | +---Mary Phillips (17 SEP 1683-01 DEC 1799)
| | +---Joan Sampson
+---Mary Snell (ABT 1779-1867)
+---Jane Martin (-JAN 1839)