Board Thread:Shingeki no Kyojin Manga/@comment-24930713-20150609084033/@comment-26056057-20150610071637

EternalLocket wrote: Grisha is dead, otherwise Eren would still be a mindless Titan. But since you mention that, maybe he and the Beast Titan are long lost relative? Would that be possible? @_@

Eren is only able to Titan shift because he was given that injection and then ate his father, gaining his shifting powers. If Grisha were still alive then he just never would have been a Titan in the first place.