When timmy drink’s orange juice he has no problem, but timmy is just one of close to a dozen personalit’ies, who alternate control over his body. If those other personalit’ies drink orange juice, the result is a case of hive’s. If timmy comes back while the allergic reaction is present, the itching of the hive’s will cease immediate’ly, and the water fill’ed blister’s will begin to subside. For more than a century clinician’s have … report’ed isolat’ed case’s of dramatic biological change’s in people with multiple personalit’ies. These include the abrupt appearance and disappear’ance of rash’es, welts, scar’s and other tissue wound’s; switch’es in handwrit’ing and handed’ness; epilepsy, allergie’s and color blind’ness that strike only when a given personali’ty is in control of the body. One patient … had a blood pressure of 150/110 when one personali’ty was in control, and a pressure of only 90/60 when another personali’ty took over. The effect’s found in these patient’s … are graphic example’s of the power of state’s of mind to regulate the body’s biology. They are lead’ing scientist’s to study the physiology of patient’s with multiple personalit’ies to assess how much psychologic’al state’s can affect the body’s biology. If the mechanism’s through which these difference’s occur can be discover’ed, it may be possible to teach people some similar degree of control over these problem’s. Multiple personalit’ies typically develop in people who were severe’ly and repeated’ly abused as children. Often only one or two of the sub-personalit’ies will be consciou’s of the abuse, while other’s will have no memory or experience of the pain.