Ignoring the eyelash/eyebrow matter, the ponytail, and the apparent breasts mentioned previously in this thread, and the way that the ears seem to more closely resemble Zelda's than Link's (also mentioned in this thread), I read up on the major dimorphism-based traits between men and women, and compared this protagonist to the Links from Skyward Sword and Twilight Princess in these traits.
The most conclusive differences I could find are as follows:
- This protagonist has a particularly low waist-to-hip ratio (that is, the character has thinner waist compared to the character's hips than SS or TP Link)
- This protagonist has thinner shoulders: TP and SS Link have broader shoulders.
- This protagonist has a rounder face than Skyward Sword's Link or Twilight Princess's Link.
- This protagonist seems to have more muscle in the back of his or her thigh, whereas Links past tended to have more muscle in the front.
- The bent knees makes this a little difficult to judge, but I think this protagonist has longer legs relative to his or her torso compared to the leg-torso ratio present in TP's and SS's Links.
It is said that the most dimorphic areas on the human body (that is, the areas that differ the most between males and females) are the chest, lower half of the face, and the waist down to the knees. If I'm accurate, then these areas all more closely resemble female characteristics on this protagonist than they do male characteristics. If I'm wrong on any of these accounts or if I'm overlooking details that make the protagonist seem more likely to be a male, do not hesitate to point them out for the sake of discussion.
If I'm accurate on these accounts yet the protagonist is still revealed to be male, it would be a testament to Link's androgyny, but Nintendo generally doesn't overlook details like this. This company knows how to make characters attractive to the player, etc., so these are most certainly not details that would simply be overlooked when designing the character.