We often speak of diseases such as phenylketonuria (PKU) and achondroplasia as having a "genetic basis." Explain whether the following statements are accurate with regard to the genetic basis of any human disease (not just PKU and achondroplasia).
A. An individual must inherit two copies of a mutant allele to have disease symptoms.
B. A genetic predisposition means that an individual has inherited one or more alleles that make it more likely that he or she will develop disease symptoms than other individuals in a population will.
C. A genetic predisposition to develop a disease may be passed from parents to offspring.
D. The genetic basis for a disease is always more important than the environment.