Moebius Syndrome is a disorder that affects the nerves of the face – the facial nerve, or the 7th cranial nerve It is very rare.
We don’t really know. Rarely it runs in families, but usually other members of the family are not affected.
One theory is that the blood supply to the affected nerves in the embryo are disrupted. Another is that there is something different about the nerves and brain themselves that make them not develop properly. Certain medicines taken during pregnancy may also cause it.