User blog comment:San&Ashitaka/TITAN THEORIES/@comment-85.247.94.126-20131016225236

I have been reading all the theories here and, I must say how can Reiner, Annie, Ymir and Bert(Also Berik) be test subjects? They come from a homeland with far more powerful "titan shifters" than them. Also when Eren is injected Grisha says "Their Memories will show you how to use it" It's wierd, whose memories, the Titans? But Normal Titans are not even Titan Shifters so there are no memories of bitting their hands to shift. So there can be 2 options, he either somehow got the DNA of a titan shifter in the serum, or had various test subjects before that led down to the current injection Eren got.

Well, about the Origin of Titans, I don't believe there was such a progressed science before, to make super human soldiers and use injections all that genetic stuff, I guess they are supernatural or something...