To date no evidence has been presented, nor any document found that connects the family of Jean Ranc to the du Ranc (Duranc) family.
John P. Ranck does a wonderful job of chronicling the history of Jean Ranc and his children as well as their time in Germany before coming to America.
He also points out that there is no evidence connecting the Ranc and du Ranc families. In reading this paper, I learned that some dubious trees were written and the connection to the du Ranc family was first suggested by a charlatan who was selling fake trees.
I spent the last three weeks searching for any possible connections and I was able to find that the connection (Jean as son to Etienne du Ranc) is wrong. Very wrong.
The first thing we should look at are the family names. Even cadet sons (second and third sons who do not inherit their father's title) keep the family name. We see that the other brothers of the du Ranc family remain as du Ranc. Indeed, those related to the du Ranc family who lived at the Chateau de Vibrac also carry the family name du Ranc de Vibrac. There are many Ranc families in France - those related to the noble family in Montpellier carry the name du Ranc, those who are not related: Ranc.
Paris is a little over 700 miles from the Ranc Chateau near Montpellier. It is completely unrealistic to think that a pregnant woman would leave the comfort of her chateau to give birth 700 miles away in Paris in 18th century France.
If we look closer at the du Ranc family, we do indeed see a son, Jean, born to Etienne and Jean. But, he is born in 1642, not in the same year, 1641, as Jean Ranc. If we search the French records, we can see that Jean du Ranc is indeed a different person than Jean Ranc of Paris. Jean du Ranc de Vibrac is given his own piece of land and he assumes the role as Lord of Coussargues.
According to Google maps, Coussargues is about 75 miles northwest of the Chateau de Vibrac:
If we dig deeper, we can find (instead of just a family tree) source document translations. In this case, we see the reading of the will for Bernadin du Ranc de Vibrac:
In part, it says:
"Judgment of nobility
Claude BAZIN, knight, lord of Bezons, adviser of the Roy, steward of the justice, police and finance in the Province of Languedoc, commissioner deputy by His Majesty to carry out the verification of the title of nobility of this.
Between the Prosecutor of the King, .. in execution of the declaration of February 8th, 1664 and decree of the Council of December 24th, 1667, ...
And Noble Marc-Antoine DURANC of VEZENOBRES, Sieur of Vibrac, Jean DURANC sieur of Coussargues his brother, noble Hercule DURANC of VEZENOBRES sieur de Ferrières and Jean DURANC sieur de Valgrand cousins first cousins of this, Marc-Antoine DURANC of VIBRAC sieur de Saint-Sériès captain and Louis DURANC his brother, cousins of said Marc-Antoine - assigned to know Marc-Antoine for Sieur Etienne DURANC his father and the late Hope of DURANC his aunt, Hercules DURANC Ferrières for the late Hercules, sieur de Valescure his ayeul and defendant.
* Testament of noble Etienne DURANC lord of Vibrac, Saint-Nazaire and other places.."
Clearly, Jean du Ranc and Jean Ranc are two entirely different people. I think it is time to end the charade that Jean Ranc is the same person as Jean du Ranc and set the record straight. Especially here at Wikitree.