# Duplessis candidate line: 1740 parentage correction

**Scope:** This analysis applies to the Québec Prime Duplessis born or baptized in 1844, who remains an unproved candidate for Oliver Prime Duplessis of Oswego. It does not assign these people as Shane’s ancestors.

The 1900 book *Les vieilles familles d’Yamachiche*, tome III, supplies a candidate line from Prime to parents Jean-Baptiste Duplessis and Christine-Placide Denoncourt, then to paternal grandparents Isidore Duplessis and Marie-Émilie Rouette. Its earlier pages claim that the family’s Jean-Baptiste dit Duplessis was a son of Louis Gastineau. The book’s own footnote acknowledges difficulty reconciling that claim.

Raymond Douville revisited the question in [“De Nicolas Gastineau sieur Du Plessis à Maurice Le Noblet Duplessis,” *Les Cahiers des dix* 39 (1974), pp. 85–117](https://doi.org/10.7202/1025318ar). His record-based findings are stronger:

- Nicolas Gastineau’s documented male descendants do not produce the later Jean-Baptiste.
- A Detroit parish record dated 10 June 1714 records the baptism of a young Mascoutin boy, about three, held in slavery; sponsor Louis Gastineau named him Jean-Baptiste.
- A 7 June 1735 notarial record concerns a Mascoutin man named Jean-Baptiste engaged for the fur trade. Douville could not establish whether he was the 1714 child.
- The 26 April 1740 marriage contract of Jean-Baptiste dit Duplessis and Françoise LaCerte says his father and mother were unknown to the Trois-Rivières parish. Its inheritance provisions say no relatives were found on the groom’s side.
- The couple’s first child, Marie-Josephe, was baptized on 25 March 1741 as a daughter of Jean-Baptiste Noblet dit Duplessis and Françoise LaCerte.

The evidence establishes Jean-Baptiste dit Duplessis, parents unknown, and wife Françoise LaCerte as the earliest defensible generation on the candidate’s surname line. It rejects the older Gastineau parentage. An identity between Jean-Baptiste and the Mascoutin child is plausible but unproved, so the archive does not present Indigenous ancestry as established.

The candidate lineage now ends as follows:

1. Prime Duplessis — notation dated 16 November 1844 in the Yamachiche genealogy; present in the 1851 Pointe-du-Lac household.
2. Jean-Baptiste Duplessis — born 2 September 1798; married Christine-Placide Denoncourt on 9 November 1824, according to the published genealogy.
3. Isidore Noblet Duplessis — baptized 25 February 1763; married Marie-Émilie Rouette in 1791, according to the published genealogy.
4. Jean-Baptiste dit Duplessis — parents explicitly unknown in the 1740 contract; married Françoise LaCerte.

Two independent identity bridges remain necessary before this becomes Shane’s documented line: a record tying the 1844 Québec Prime to Oliver Prime of Oswego, and evidence tying the 1740 groom to the 1714 Mascoutin child if that earlier origin is to be claimed.