Anybody can just say that they're a demi-god of so-and-so. It's better to find the reason why a person says such a thing.
So, the royal family of Japan has a legendary history of being related to the sun goddess Amaterasu. Cleopatra, a famous Egyptian princess, was honored as the daughter of Isis. The same claims were made, if I recall correctly, by Aztec royalty and Cambodian royalty. What do they have in common? POLITICS. That's all it is. The "power of the god" was granted to them as royal lineages who already had power over other people. Would you argue with a king if he feels like claiming godhood?
The kumari of India are children who are identified as the incarnations of the goddess Kali and are taken away to be worshipped until they reach puberty. Really, they seem to me, ordinary girls who get caught up in cultural traditions.
In my opinion we are all divine, or none of us are.