Sosie is one of five winners out of Sosia (Shamardal), a winner who was stakes-placed in France. Her other produce includes Uther (Camelot), a Group winner in France who took the Gr.3 Prix Noailles, the Listed winners Anasia (Intello), also multiple Group-placed in France, and Copie (Iffraaj), whose Listed win came in Germany, and Sosino (New Approach), who was second in the Gr.3 Prix Daphnis.

Second dam Sahel (Monsun) was a winner and produced eight other winners. They include the champion Sortilege (Tiger Hill), who won the Premio Lydia Tesio, then a Group 1, and Soudania (Sea The Stars), winner of the Gr.3 Prix du Prince d'Orange. Sortilege is the dam of the Group 3 winner Sirjan and of Spanish Eyes, second in the Gr.1 Preis der Diana.

Third dam Sacarina (Old Vic) never raced but produced nine winners besides Sahel. Among them are three Group 1 winners, all by Monsun: the champions and sires Samum and Schiaparelli and the filly Salve Regina.

Sosia has a yearling full-brother to Sosie named Jumeau and a filly foal, also a full sibling, named Similitude. She was covered again by Sea The Stars in 2025.