Warm Heart is out of Sea Siren (Fastnet Rock), who won three times at Group 1 level in Australia over sprint distances. Sent to Europe, she was highweighted among older mares in Ireland at five to seven furlongs and ended her career by winning the Listed Belgrave S. Sea Siren is also the dam of Warm Heart's 3-year-old full brother Bremen, a maiden winner, and of her full sister Celestial Object, a winner who was second at Group 3 level. Sea Siren is a half-sister to Oratorio (Stravinsky), a Group 3 winner in Australia and a sire, and to Lady Dehere (Dehere), a Group 2 winner in New Zealand and dam of the dual Group 2 winner Oracy and the Listed winners The Lady and Lady Maroal.

Second dam Express A Smile (Success Express) did not race. She is a full sister to Snapshots, a Listed winner and Group 2-placed.

Third dam Hold That Smile (Haulpak) won the Karrakatta Plate, then a Group 1.

The family also includes Ruthless Dame (Tavistock), winner of the Gr.1 Robert Sangster S.

Back in Australia, Sea Siren foaled a colt by Camelot in August 2022 and a colt by Home Affairs (I Am Invincible) last August, and she was then covered by Justify.