The scientific study of the principles of heredity and the variation of inherited traits among related organisms.

Reference for tag wiki excerpt.

What is Genetics?

by By Dr. Ananya Mandal, MD (published originally in news-medical.net)

"Genetics is the study of heredity. Heredity is a biological process where a parent passes certain genes onto their children or offspring. Every child inherits genes from both of their biological parents and these genes in turn express specific traits. Some of these traits may be physical for example hair and eye color and skin color etc. On the other hand some genes may also carry the risk of certain diseases and disorders that may pass on from parents to their offspring."

A Brief History of Genetic Science and Regulation by gmeducation.org