I somewhat agree with that theory, but if we look at Adam, both of his eyes are gray. Technically, they aren't heterochromatic. Meanwhile, the scientist, his past lover, has one gray eye and one black eye, while his current lover, the one with black hair, has one black eye and one green eye.
So I think Eve actually gave Adam both of his eyes, and they changed to gray to match Adam's body. If the scientist had given Adam his eyes, wouldn't Adam have ended up with heterochromia, just like the scientist himself? But Adam has two identical gray eyes, which makes me think that both of them came from Eve instead.
The reason I think Eve could have done this is that he seems to have the ability to regenerate his body. I don't know if that's actually confirmed, but it's just my theory that Eve is essentially the father of them all. If he really can regenerate his body parts, he could have given Adam both of his eyes and then simply regenerated his own afterward.
As for the scientist and his current lover, the scientist's eyes were also gone due to the same reason leaving him blind, while his current lover gave him one of his own eyes in return. So, technically, I don't think the scientist donated any eyes to Adam at all. Otherwise, wouldn't Adam have inherited the scientist's mismatched eye colors? Of course, this is just speculation, but I think it makes more sense this way.
? the scientist did not have heterochromia when both adam and him were young. Both got gray eyes, check final chaps from season one before Michael brainwashed Adam. I'm saying that gabriel, the scientist's lover, made a deal for him to not go completely blind with replacing adam's gray eyes. So, they, gabriel and the scientist, both share a blind eye (adam's) and a black eye where I suspect that the black eyes were from Gabriel. Gabriel perhaps did a modification for the gray-blind eye as he is an esper, like to be sharp for battle. So, that's why he got a hint of green.
good time to re-write my other theory.
Adam's past lover, the scientist, exchanged his eyes for Adam as they got fcked up after the suicide incident & side effects of guiding Eve/Michael (remember, enhancers got side effects, one prominent one like blindness). Perhaps they found that they both got blood compatibility, so that's why he made up his mind. Nonetheless, the scientist's current lover/f buddy/esper (?), forgot name, also gave the scientist his eyes so that he would not go completely blind. Therefore, both share one blind gray eye (Adam's) & one black eye (scientist's current lover, gabriel?).
Look, previous season back memories, the scientist got the same gray color eyes as Adam but in the "present" he got one gray and the other black. I believe that happened. Additionally, the scientist's current lover/esper got enhanced his "blind" gray eye as it got a hint of green, so to still perform his esper's duties without being hindered by a blind eye.