Genetics is the branch of biology concerned with the study of heredity and variation. It studies the science of genes, their molecular structure and function in a living cell or organism.
Since genes are essential to all living organisms, Genetics is a wide discipline and studies can range anywhere from viruses to the most complex eukaryotes.
Gregor Mendel (1822-1884) is frequently credited with being the "father of genetics" with his description of inherited traits in plants. Applying mathemetics to the way in which distinct features of a plant were passed to offspring, Mendel was able to describe the inheritance patterns of traits through ratios.