A. J. Jacobs's interest in genealogy started when he received an email from his twelfth cousin. Since then, Jacobs has joined one of the world's biggest family trees on Geni.com, which includes more than 75 million people. Jacobs believes that if we all realized that we're connected in this way, a lot of the problems in the world could be solved. As Jacobs says, "We're not just part of the same species. We're part of the same family.