According to Clyde Francks, a gene called LRRTM1, found on chromosome 2p12, can be a strong contributing factor determining left-handedness but is not essential. This gene affects brain symmetry which is associated with schizophrenia. Those with this gene need not fear for there is only a slight increase in developing certain mental illnesses.
Sandy: So I could have gene LRRTM1, not be left-handed and not be schizophrenic.
Sandy’s year long journey – going from being a right-hander to left-hander, and Kelly’s parallel trip as a left-hander doing things as a right-hander.