RL Agnes Tachyon retired very early (just four races!) because of a leg injury. Superficial digital flexor tendinitis (AKA "bowed tendon", that is tendon became inflamed and swells into a bent or "bowed" appearance) on his left foreleg.

Agnes Tachyon's dam, Agnes Flora, also retired early because of a leg injury. Fracture on her left foreleg.

Agnes Tachyon's daughter, Daiwa Scarlet, retired barely past her prime because of a leg injury. Which injury? Why, bowed tendon on her left foreleg, exactly the same injury that caused the retirement of her sire.

Most of Agnes Tachyon's foals also developed chronic leg problems that forced them into early retirement. Deep Sky (bowed tendon on left foreleg), Ridill (osselet of left foreleg fetlock), Reve d'Essor (cleavage fracture of right hindleg), and so on. Yeah, it's genetics, with the genes being inherited from Agnes Flora to Agnes Tachyon and then to Tachyon's foals.