Due to Genetic Differences Genetic variability is one of the major contributors to drug and chemical sensitivity.
Genetic variability exists between all individuals to one degree or another.
This variation is the basis for all evolutionary change and our biological existence. The source of this variation occurs as DNA in ovum and sperm cells mutates, recombines, and is passed down to our offspring. Some mutations impart the ability to fight disease while others put us at a disadvantage, and others yet seem to impart no obvious changes at all. The passing of genes to our offspring leads to familial genetic traits such as brown hair or even the ability to effectively metabolize carcinogens found in tobacco. The passing of genes over thousands of generations results in genetic traits that reach beyond the immediate family and may extend throughout a nation or race of people.