Genetics is the branch of biology which deals with inheritance and variations of characters from parents to offspring.
Father of Genetics is Gregor Johann Mendel.
Inheritance is the process of passing characters from parent to progeny. It is the basis of heredity.
Variations is the degree by which progeny differs from parents. Variations can be in terms of physiology, morphology and behavioral characteristics of individual belonging to same species. Variations arise due to reshuffling of chromosomes, crossing over, mutations and effect of environment.