Helena and Sarah were born a month after Cosima (who if I'm remember correctly, is the oldest clone), based off the birth dates supplied in S1. So unless Sarah's birthdate is truly a lie, then it's not possible for Sarah and Helena to be the "original" clones. But that being said, if the disease WAS caused by the…

I can't help feeling like Delphine is forcing herself to be so emotionally detached from all of this — much like Cosima seems to be (e.g., thinking of the clones as "others" and depersonalizing them) — in order to keep moving forward with the science. IMO, it felt to me like Delphine was trying really hard to keep it…

Cosima really does need the glasses, otherwise Sarah wouldn't need to constantly have to keep looking over them to see properly. Also, Cosima seems have myopia, which is linked to higher levels of intelligence/education (research suggests this leads to more reading, which in turn leads to degeneration of the eyes).