It is interesting to read that Einstein's brain was smaller than average. Einstein was also viewed as having "delayed development" as a child, which is not exactly typical for a so-called budding "genius" l) . Added to the fact that it is known that Einstein deliberately plagiarised wholesale from Poincare's work, among many others:-
it would not surprise me if everything Einstein claimed, such as "nothing can go faster than the speed of light" is also dead wrong. Maybe FTL travel is indeed possible after all!