(ABT 1732-)
+---William Tretheway (ABT 1766-)
| +---Elizabeth Skinner 
(ABT 1736-ABT 1800)
+---Richard Tretheway (ABT 1793-)
| +---Rebecca Haines (ABT 1770-ABT 1820)
+---John James Tretheway (04 MAY 1841-09 OCT 1912)
| +---Ann Spargo (ABT 1801-BEF 1851)
+---John Spargo Tretheway (30 JUN 1866-)
| +---Mary Jane May (ABT 1847-31 JUL 1930)
+---Bernard Tretheway (ABT 1900-)
| | +---James Buckland
| +---Jane Buckland (ABT 1864-ABT 1928)
| +---? Friend
+---John Tretheway (10 MAR 1930-)
| +---Henrietta Agnes McConnell (09 FEB 1903-28 FEB 1977)
Sharon Margaret Tretheway (27 OCT 1962-)
| +---Robert Pitcaithly
+---Jeanette May Pitcaithly (24 APR 1934-)
+---Annie May Coxhead