She was married to Louis Jan "Jack" Roosmale Nepveu (August 8, 1928 – April 9, 2013). Her husband, a Dutch commoner born in Pretoria, South Africa was previously engaged to Princess Marie Louise of Bulgaria but the wedding did not take place. They have two children.
Born Monique Louis-Dreyfus, she was one of three children born to Jean and Jeanne Madeline (née Depierre) Louis-Dreyfus. Her brother is Robert Louis-Dreyfus and her sister is Marie-Jeanne Meyer. Her Father was Jewish and her mother Roman Catholic. She is the great granddaughter of Léopold Louis-Dreyfus, founder of the Louis-Dreyfus Group, which had begun buying and selling wheat in the Alsace region a century earlier, and rapidly Diversified into shipping, oil and other commodities. Her grandfather was Louis Louis-Dreyfus who served in the French Parliament during the French Third Republic. After the death of her brother Robert, his widow and second wife Margarita Louis-Dreyfus (born Rita Bogdanova), inherited 60% of the Louis Dreyfus Group (later increased to 65% in 2012). Monique owns 12.5% of the Louis Dreyfus Group making her a Billionaire.