GENETICS AND ENVIRONMENT

Although genes produce an effect, environment also makes a contribution to the final product. The interplay of these two factors is popularly referred to as the interaction of " Nature" and " Nurture " in the determination of human traits. In some cases however, there is no interaction of both genetic and non-genetic factors while in others mutant genes do not act in isolation, but are influenced by the action of other genes. These variable interactions will now be illustrated using the many examples of inheritance we encounter in clinical medicine.