Scylla is out of Close Hatches (First Defence), champion older mare and a five-time Grade 1 winner, who was second in the 2013 Grade 1 Distaff and took an Eclipse title in 2014. Close Hatches has bred three Graded winners, among them Scylla's full-brother Tacitus, a multiple Grade 2 winner who was multiple Grade 1-placed, and the full sibling Batten Down, winner of the Grade 3 Ohio Derby and Grade 2-placed.

Second dam Rising Tornado (Storm Cat) won once and has six winners. Among them are Lockdown (First Defence), a full-sister to Close Hatches, who won the Listed Busanda Stakes, was Grade 1-placed and is the dam of the multiple Grade 1 winner Idiomatic, winner of the 2023 Grade 1 Distaff, and Hail (Tapit), a winner placed in the Listed Busanda Stakes and dam of the Grade 3-placed winner Burning Glory.

Third dam Silver Star (Zafonic) won once at two, was third in the Listed Prix Coronation and produced eleven winners. They include Barsanti (Champs Elysees), winner of the Listed Buckhounds Stakes and Group 2-placed, and the winner Bird Flown (Oasis Dream), dam of the dual Group 1-winning sire Siskin. Silver Star is a full-sister to the dual Group 1-winning sire Xaar.

Close Hatches descends from Best in Show, the 1982 Broodmare of the Year, as a great-great-granddaughter.

Close Hatches has an unraced 2-year-old filly, Crowning Glory (Uncle Mo). Covered by Gun Runner in three straight years, she has a yearling filly and a weanling colt by him and is due a further full sibling to them in 2026.