This year true life followed fiction as Lord Peter Melchett was found not guilty on similar charges. Normal human variation Human genetics is concerned with the causes and alleviation of disease. There are many traits which are the products of variation in the forms of a single gene present in different individuals. King Louis XIV of France was born in this way, much to the distress of his wet nurses colour blindness - there are several forms but the most common, affecting about one male in twelve, is deuteranopia , the inability to distinguish between red and green. It is caused by a missing gene which codes for one of the visual receptor pigments.
Genes can affect behaviour.
In some cases we can begin to understand why because the gene in question is responsible for the production of a neurotransmitter or receptor. Other cases are so bizarre that we cannot even begin to guess what is the underlying cause. The symptoms vary from no more than minor patterns of repetitive behaviour, motor ticks, to the most notorious symptom, an uncontrollable involuntary urge to utter swearwords and obscenities. They have an exaggerated startle reflex and will jump to obey any abruptly uttered command however dangerous or foolish it may be. Monoamine oxidase is an enzyme which acts to destroy certain neurotransmitters such as dopamine.