I am looking for a YA novel, which I read in German, around 2012.
I might be mixing different books here, but the story roughly goes like this:
Gifted children are kept in some kind of research facility to investigate their powers. There might've been multiple children, but the focus lies on twins that are able to communicate telepathically.
The point-of-view changes between different characters, but in one of the key scenes, the evil doctor overseeing the experiments figures out that their power must stem from the fact, that they are missing the "corpus callosum" (the part of the brain connecting the two brain hemispheres).)
I think the protagonist was a young woman being recruited for the facility, who later ends up helping the children escape.
Also I believe there was a scene early in the book where the twins play chess telepathically, which the protagonist is astounded by.
I tried googling, but was only able to find Time for the Stars and The Twinning Project but those aren't what I am looking for.
This story has really been bugging me for a while, so any help would be greatly appreciated.