(ABT 1867-)
| +---James Trethewy 
| +---Richard Trethewy (ABT 1665-JAN 1741)
| +---John Trethewey (ABT 1690-)
| | +---Ann Martyn (ABT 1666-JUN 1738)
| +---Joseph Trethewy (ABT 1735-DEC 1816)
| | | +---Phillip Mellow (ABT 1660-JAN 1711)
| | +---Temperance Mellow (ABT 1690-MAY 1765)
| | +---Jane ?
| +---John Trethewey (ABT 1764-JAN 1834)
| | | +---John Rickard
| | | +---Jonas Rickard (ABT 1705-)
| | +---Caroline Rickard (ABT 1734-)
| | +---Honour ?
| +---Joseph Trethewey (ABT 1793-)
| | +---Charity Strangeman (1756-)
| +---John Trethewey (ABT 1817-1890)
| | | +---Benjamin Warrick
| | +---Elizabeth Warrick (ABT 1788-)
| | +---Jenifer ?
+---Elizabeth Ann Trethewey (ABT 1840-)
| +---Richard Hicks
+---Ann Hicks (ABT 1820-)
+---Philadelphia ?