Information for Those Receiving a Questionnaire

Confidentiality Provisions: For all studies conducted at the University of Southern California approval from the Human Subjects Review Board is required. Any questions may be directed to Dr. Mack, the Principal Investigator, at 888-328-6478. A letter is sent out to each twin prior to sending the questionnaire. As described in the letter, participation in the study is entirely voluntary and all responses are kept confidential.


Need for both twins to participate: Since the main advantage of studying twins is to be able to compare disease and exposure experience within pairs, it is very important to have information about both twins, preferably. While information from one twin is also valuable, we strongly encourage both twins to participate!

Benefits of participation: We can’t pay you or promise you instant results regarding a disease you may have a particular interest in; however we can assure you that your participation will be a very valuable contribution to the scientific study of causes of disease. We are planning to provide a service to twins who want to verify their zygosity (i.e. whether they are identical or fraternal), by offering zygosity testing at a nominal fee. We will let you know by the website when this becomes available.

Subjects covered by the questions: We have tried to cover most of the important areas of life without being intrusive or taking up to much time. All of the questions are answered by checking off boxes. The subjects covered include the family, growth and development, lifestyle (such as smoking, dietary, and exercise history), education and occupation, medical history, and health practices.