Human Genetics 13th Edition by Ricki Lewis. This ISBN is student textbook only. It does not come with online access code. Access code, if required by an instructor, sold separately at another ISBN. The content of International edition is the same as other formats. Today, human genetics is for everyone. It is about variation more than about illnesses, and increasingly about the common rather than about the rare. Once an obscure science or an occasional explanation for an odd collection of symptoms, human genetics is now part of everyday conversation. By coming to know genetic backgrounds, people can control their environments in more healthy ways. Genetic knowledge is, therefore, both informative and empowering