Genetic Component of Handedness

Some functions are generally controlled by the right side of the brain and others by the left. One of the most easily observed examples of this "lateral specialization" of the brain is handedness-that is, a person's preference for using either the right or the left hand. This study will try to determine how the genetic component of handedness is inherited. It will test the theory that a single gene is involved in determining handedness and will try to locate the gene. Families with at least two left-handed siblings aged eight years or older and at least one right-handed parent are eligible to participate in this study. The left-handed siblings and both parents will fill out a brief questionnaire on hand usage, obtain a tissue sample taken from inside the cheek, and return the questionnaire and the sample by mail to the study researchers. The tissue sample will be used for DNA gene mapping. Participants will be given a kit and instructions for obtaining the sample, along with mailing envelopes. Cheek swab sampling basically involves using a small brush to gently brush a layer of cells off of the inner wall of the cheek and then dropping the brush tip into a preservative. The information gained from this study may provide insight into aspects of brain development that can be of medical benefit in the future.