| Father | Roger MORTIMER [EARL OF MARCH] (1287 - 1330) |
| Mother | Joan De GENEVILLE [COUNTESS OF MAR (1285 - 1356) |
| Sibling | Margaret De MORTIMER (1308 - ) |
| Sibling | Catherine (Katherine) De MORTIMER [COUNTESS OF WAR (1309 - ) |
| Sibling | Agnes De MORTIMER [COUNTESS OF PEM (1313 - ) |
| Sibling | Roger De MORTIMER (1308 - ) |
| Sibling | Joane De MORTIMER (1313 - 1351) |
| Sibling | Edmund De MORTIMER [SIR KNIGHT] (1306 - 1351) |
| Sibling | Maud De MORTIMER (1307 - 1345) |
| Sibling | Geoffrey De MORTIMER [SEIGNEUR OF COU (1310 - ) |
| Sibling | Joane De MORTIMER (1314 - 1337) |
| Sibling | Blanche De MORTIMER [BARONESS GRANDI (1316 - 1347) |
| Sibling | John De MORTIMER (1321 - ) |
| Sibling | Beatrice De MORTIMER [BARONESS BREWOS (1322 - 1383) |
| Sibling | Geofrey MORTIMER Sir ( - ) |
| Sibling | John MORTIMER ( - ) |
| Sibling | Katharine MORTIMER (1319 - ) |
| Sibling | Agnes MORTIMER ( - ) |
| Sibling | Matilda MORTIMER ( - ) |
| Sibling | Blanche MORTIMER ( - ) |
| Sibling | Beautrice MORTIMER ( - ) |