The name is a variation of "Dumas," and we also see Dumet, Dumets, Dumes, Dumeiz, etc - it comes from medieval French mas, "farmhouse," and is very common.

Adrien Demers or Dumoys was a farmer in Étoutteville, a very small village (449 people in 1999; above is a sketch of its chapel of St-Cosme). It is in Normandy inland from Dieppe. Adrien's wife's name was Catherine Pougnye, and they were married there in August 1594. We know of one son, Jehan.

Jean or Jehan Demers (born about 1600) lived in the port of Dieppe, like many other Québecois ancestors; it was a major starting point for voyages to the New World. He married twice in Dieppe (Miotte Lecombe and then Barbe Mauger) and had several children who accompanied him to Québec in 1644. Known children of Jean are André, Laurent, Jean and Catherine; it is not certain if any of these were Miotte's children, but when Jean the younger (born 1633) was married he named Barbe as his mother. Both wives had apparently died by the time the elder Jean decided to come to Canada. The sons are the ancestors of all later Demers families in Canada. They settled in Sillery, where Jean Demers in November 1654 at Nôtre-Dame de Montréal married sixteen-year-old Jeanne Voidy, daughter of Michel Voidy and Catherine Dorbelle (she died in Québec city in 1708. This is not the same Jeanne Voidy who married Nicolas Pelletier; they came from different towns in France and died at different times and places in Canada; but it is not unreasonable to think they were related.).

They had twelve children: François (1658-1687); Marguérite (1659-1672, see below); Jean (1661); Pierre (1663-1714); Anne (1665); René (1667-1725); Marie-Madeleine (1669); André (1671); Eustache (1673-1708); Catherine (1675-1693); Nicolas (1677); and Michel (1681-1701).

Marguérite Demers married André Bergeron in July 1673, at the age of fourteen; she had twelve children (see Bergeron).

At the time of the 1667 census Jean Demers the younger owned a small farm just outside Québec city, with one "horned beast," but in 1681 he had a much larger farm, and eight animals as well as a gun. By 1695 he also had a townhouse.