User blog comment:MeDeoPal/On the Origin of Titans and Shifters/@comment-112.198.90.111-20130811074800

hmmm... It's a good theory, though it could be debunked where you stated titan-shifters turned other humans into titans. So far only eren was the only one turned into a titan by a titan, Eren (by his father, though he was in human form at that time, but still).