If champion Essential Quality can rebound in Saturday’s Belmont S. (G1), he would become a record-equaling fourth winner sired by Tapit. The only stallion to achieve that feat is the 19th-century patriarch Lexington, who sired General Duke (1868), Kingfisher (1870), Harry Bassett (1871), and Duke of Magenta (1878).

Tapit is already in exclusive company as the sire of three Belmont winners. He is the first to join that club since the all-time great Man o’ War, responsible for American Flag (1925), Crusader (1926), and Triple Crown sweeper War Admiral (1937).
Man o’ War was following in the hoofsteps of his sire, Fair Play, who also had three winners. Aside from Man o’ War himself, the conqueror of the 1920 Belmont, Fair Play sired Mad Play (1924) and Chance Shot (1927). 
Fair Play descends from the other sire with a Belmont troika – *Australian, who got Joe Daniels (1872), Springbok (1873), and Spendthrift (1879). Spendthrift had a Belmont-winning son, Hastings (1895), in turn the sire of Fair Play who was second in the 1908 edition to the undefeated Colin. If not for Hall of Famer Colin’s thwarting Fair Play, there would have been a continuous sequence of father-and-son Belmont heroes through Man o’ War’s progeny. 
Tapit represents another sire line known for classic success. He hails from the male line of 1977 Triple Crown legend Seattle Slew and 1992 Belmont-winning Hall of Famer A.P. Indy
In addition to his Belmont trio of Tonalist (2014), Creator (2016), and Tapwrit (2017), Tapit is the grandsire of last year’s hero, Tiz the Law, by Tapit’s son Constitution. Four more Tapit sons have placed in the “Test of the Champion.” Two took minor awards behind Triple Crown champs – Frosted was best of the rest to American Pharaoh (2015), and Hofburg was third to Justify (2018). Tacitus was runner-up in 2019, and Lani was third to fellow Tapit Creator in 2016. 
Essential Quality has a less happy Belmont connection through his dam, Delightful Quality. By Elusive Quality and descended from Grade 1 queen Basie, Delightful Quality is related to Smarty Jones, who lost the Triple Crown when Birdstone caught him in the 2004 Belmont. 
Further back, Essential Quality traces to blue hen *La Troienne, the family labeled 1-x. *La Troienne is herself the dam of Hall of Famer Bimelech, the 1940 Belmont winner. Bimelech’s full sister, Big Hurry, is the ancestress of 1989 Belmont romper Easy Goer. 
Belmont rival Overtook also descends from *La Troienne, via her granddaughter Striking, the same avenue as Essential Quality. But Overtook belongs to the branch of the family that produced 2010 Kentucky Derby (G1) hero Super Saver and Bluegrass Cat, the runner-up in the 2006 Derby, Belmont, and Travers S. (G1).
Overtook is one of two entrants by Hall of Famer Curlin, along with Known Agenda. Curlin is also the broodmare sire of France Go de Ina. Just denied by champion filly Rags to Riches in the 2007 Belmont, Curlin went on to sire a Belmont winner in Palace Malice (2013). 
Overtook’s dam, 2015 Spinster (G1) heroine Got Lucky, is bred on the same cross as Rags to Riches. Both are daughters of A.P. Indy and royally bred mares by Deputy Minister. Curlin is himself out of a Deputy Minister mare, so Overtook is inbred to that Canadian Hall of Famer.  
Known Agenda’s dam, Byrama, is also a major winner having taken the 2013 Vanity H. (G1). Byrama narrowly beat Charm the Maker, dam of Rock Your World, in the 2012 Unzip Me S.
Rock Your World’s dam is by 2003 Belmont star Empire Maker, who is the paternal grandsire of American Pharoah. Rock Your World’s sire, unbeaten Candy Ride, shares the same male-line ancestor as Empire Maker, Fappiano.
Preakness (G1) hero Rombauer is by Candy Ride’s son Twirling Candy. Rombauer has further links in common with Rock Your World on their dams’ side. Rock Your World’s second dam (maternal granddam) is by Europe’s “Iron Horse” Giant’s Causeway, and Rombauer’s dam is by the Giant’s Causeway stallion Cowboy Cal. 
Moreover, Rombauer and Rock Your World share the same sixth dam in the matrilineal line, *Albany Isle. They belong to the family labeled 9-f, as does Known Agenda, but from a far more remote ancestress. Other members of the 9-f tribe are responsible for four Belmont winners – Bold Forbes (1976), Coastal (1979), Creme Fraiche (1985), and Bet Twice (1987).
Both of Bourbonic’s grandsires are Belmont winners. Sire Bernardini is by the aforementioned A.P. Indy, and Bourbonic’s broodmare sire is Afleet Alex, the 2005 Belmont conqueror. Afleet Alex is already the broodmare sire of 2019 Belmont scorer Sir Winston.
Bourbonic is out of Grade 2 vixen Dancing Afleet, who traces to a full sister to Hall of Famer Native Dancer, the 1953 Belmont winner. This is the family dubbed 5-f, also the tail-female line of 1949 Belmont victor Capot. 
Native Dancer’s paternal grandson, Mr. Prospector, has the most male-line descendants in the field with five. The representatives of “Mr. P” are the Curlin sons Known Agenda and Overtook and three tracing to Fappiano. In addition to Rombauer and Rock Your World, France Go de Ina descends from Fappiano via another branch, Unbridled
Hot Rod Charlie and France Go de Ina are renewing the rivalry of their respective sires, Oxbow and Will Take Charge, from the 2013 Triple Crown trail. Although Will Take Charge edged Oxbow in the Rebel (G2) and ended the year as champion three-year-old male, Oxbow finished ahead of him in all three jewels. Oxbow won the Preakness and placed second in the Belmont, while Will Take Charge was unplaced throughout the Triple Crown. 
France Go de Ina hopes to become the first Japanese shipper to win a Triple Crown race. He is also trying to score a first Belmont victory for the family labeled 5-j.
Hot Rod Charlie belongs to the same 11-d family as Thunder Gulch, the 1995 Derby and Belmont champion. But their maternal connection is buried back in the 19th century, and Hot Rod Charlie faces a stamina question based on a nearer relation. Out of an Indian Charlie mare, Hot Rod Charlie is a half-brother to champion sprinter Mitole, who stretched his speed a mile in the 2019 Metropolitan H. (G1).
The lone representative of the Northern Dancer sire line in Saturday’s Belmont, Hot Rod Charlie is one of just two entrants who do not descend at all from Secretariat. The other devoid of Secretariat is Known Agenda.
Six of the eight Belmont entrants have the 1973 Triple Crown legend appearing somewhere in their ancestry through his daughters. Essential Quality counts Secretariat three times.