Spoiler discussion: I've only seen a bit of an abridged series of AoT but I know enough from /a/ thread headers that there's big people that eat people, and a basement or attic, andapparently the main character(s) are somehow genetically the big people?
Yes, they have the genetics to become the Titans. It's not something someone sane would want to be since they're mindless.Only a few can be Titan shifters which can switch between the two forms and keep their intelligence in both.