| Father | Marmaduke Thweng - Lord of Kilton Castle II (1225 - 1282) |
| Mother | Lucia De Brus (1225 - 1282) |
| Sibling | Marmaduke De Thwenge (1256 - 1323) |
| Sibling | Hillaric Thweng (1258 - 1322) |
| Sibling | Matilda Thweng (1265 - ) |
| Sibling | Margery Thweng (1276 - ) |
| Sibling | Hillaria Thwenge (1258 - ) |
| Sibling | Sir John De Thwenge of Cornburgh (1261 - 1330) |
| Sibling | Sir Robert Thwenge, 1st Lord Thwenge (1252 - 1279) |
| Sibling | Gawain Thweng (1259 - ) |
| Sibling | Richard Thweng (1267 - ) |
| Sibling | Peter Thweng (1270 - ) |
| Sibling | Johanna Thweng (1271 - ) |
| Sibling | Roger Thweng (1274 - ) |
| Sibling | Margery De Thweng (1266 - ) |
| Sibling | Sir Edmund Thweng of Cornburgh, Knight (1251 - 1330) |
| Sibling | Margaret Thweng (1246 - ) |
| Sibling | Robert De Thweng Lord of Kilton (1255 - 1284) |