Can different personal experiences affect our genes? Find out in an intriguing case study about one twin who is diagnosed with mental illness and her identical twin who fears she may suffer the same fate. Designed for college-level biology or genetics, the first few pages could definitely be used in a regular high school biology class while examining heredity. An AP class could delve even deeper into the DNA aspect of the lesson, making the activity one that could be easily differentiated. There are references in the teacher notes to an answer key, but it is pasword protected; it should not, however, prevent you from being able to use the case study and accompanying activities in your classroom.