how to fix object movement in GE?

hi, im trying to make something that will be like an armature (each obj have obj before him as a parent)
its kind of works but when im trying to rotate the one of the parents the objects that are higher then that one are moving not in the same way like the parent (moving from side to side while continue to rotate with the parent). how can i fix it?
test.blend (528 KB)test.blend (528 KB)

Ensure all parents have a homogene scale. The best is a scale of (1,1,1).