TEL AVIV, March 19 (Reuters) - The head of a company that says it has produced the first cloned humans said on Wednesday it would show proof at a gathering of some of the parents in Brazil next week. Clonaid, a company founded by the Raelian movement that believes mankind was created by extraterrestrials, announced in December that it had made the first cloned human, a baby girl called "Eve" born on December 26 to an American mother. Brigitte Boisselier, president of Clonaid, said three more cloned babies had been born since and some of the parents as well as...