Jacqueline de Mezieres is supposedly the mistress of Charles Lennox, 1st Duke of Richmond, and the mother by him of an illegitimate daughter Renée Lennox. She will be found in many Internet genealogies and biographies, including in the Wikipedia article of Charles Lennox, 1st Duke of Richmond.
The Wikipedia article doesn't mention Jacqueline's ancestry, but according to this genealogy, Jacqueline is herself an illegitimate daughter of Louis Joseph de Bourbon, Duc de Vendome, and Jeanne de Meziere (1660-95), and Jeanne is also an illegitimate daughter of Henri de Orleans Meziere (born 1621) and Catherine Francoise de Bretagne, and Henri is an illegitimate son of Marie de Bourbon, Duchesse de Montpensier, (died 1627) and Leonor de Orleans, Comte de St Paul, Duc de Fronjac (died 1622).
Although Louis Joseph de Bourbon, Duc de Vendome, Catherine Francoise de Bretagne, Marie de Bourbon, Duchesse de Montpensier, and Leonor de Orleans, are all historical and can be found in any history or genealogy of the period (though sometimes under slightly different names or titles), the same can't be said for their respective relationships and illegitimate children.
A search of various reliable secondary sources, failed to find any mention of this line of illegitimate children, and the issue is exacerbated by the fact that the genealogy referred to above doesn't itself cite any references, and is the work of just one person.
If half of her immediate ancestors don't seem to have existed, then it seems possible that Jacqueline de Mezieres herself may never have existed. Even if she had a humbler background, there are also doubts about the existence of her daughter Renée Lennox, which suggests that the relationship with the 1st Duke of Richmond may also be false.
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