Note: At the end of his teachings, the Hero's Spirit said that he accepted the role as the hero long ago. This implies that he may be an earlier ancestor of Link. This theory is also supported by the Hero's Spirit saying the following to Link: "Go and do not falter, my child!" Though this in itself is not conclusive evidence, since many mentor-like characters in several stories refer to their young charges using the phrase "my child," it does serve to leave open the possibility of Link being his actual blood descendant.
Further more, evidence of the Hero's Spirit being an ancestor of Link is given just prior to learning the Mortal Draw. The Hero's Spirit said that the skills he taught Link were forgotten ways that "do not leave our bloodline"[1]. He implicitly used the word "our" instead of "my". This clearly indicates that Link and the Hero's Spirit are indeed related. The Hero's Spirit was once one of the many great heroes of Hyrule[2]. It is still not known if his name was once Link as well, or perhaps even is the same man who became the Hero of Time. However, one thing that supports he may be the Hero of Time is that most of the songs used to summon the Golden Wolf are from Ocarina of Time and Majora's Mask, but why the Ballad of Gales is included is unknown.
In regards to physical appearance, the way the Hero's Spirit moves his feet is similar to the way Link moves his feet in Ocarina of Time when he targets an enemy. Lastly, in both Wii and GameCube versions of Twilight Princess, Link and the Hero's Spirit both wield their swords in the same hand. The GameCube version (the version in which the game world was originally meant to be portrayed) shows Link to be left-handed. In every past game of the Zelda series, Link's sword-hand has always been his left one,[1] whereas there's been no other left-handed person to date in a Zelda game except in the Wii version of Twilight Princess.
It is also very worth noting the blade that the Hero's Spirit holds whenever he's seen in-game. The hilt is completely unrecognizable, although, along with the armor he wears, it appears archaic and much older than most of Link's gear was in Twilight Princess, or in Ocarina of Time for that matter. However, what makes this sword special is the blade: it is (or is at least an identical copy of) the blade of the Master Sword. Not only are the shapes and sizes consistent, but the two blades are the same right down to the etched emblem portraying the Triforce just above the hilt. Granted, the blade is worn, cracked, and tarnished, but when seen crossed with the real Master Sword during training, the fact is hard to ignore. Whether this is purely symbolic or is indicative of the Shade's true identity is still left undefined, but this glaring resemblance would imply that perhaps the Hero's Spirit was, in life, one of the few wielders of the Master Sword.
