Eustache was the son of unknown parents. The date and place of his birth have not been found.
His wife is not known. They were married, but the date and place have not been found. Their only known child was Guermond I (<1013-1085).
| Attribute | Date | Description | Details | Source | Multimedia | Notes |
|---|---|---|---|---|---|---|
| Nobility Title | sire de Picquigny |