Genetics is the study of biological inheritance. Geneticists examine a wide variety of inherited traits, from the ability to bear large numbers of fruit in trees, to eye color in mammals. This discipline is a major cornerstone of the larger field of biology. People who study it do so in a wide variety of situations, from research laboratories to pharmaceutical companies, and new breakthroughs are consistently being made.
Humans have understood genetics on some level for thousands of years. They have been improving crops and animals through breeding for quite some time, selecting desirable traits and attempting to propagate them. Casual observations have also been an important part of human life for thousands of years, with people noting that members of certain families tend to have distinctive anatomical features. The Hapsburgs of Austria, for example, are famous for their prognathic jaws.
In the 1800s, a monk named Gregor Mendel began doing controlled experiments with peas which were designed to unravel the mysteries of gene inheritance. He is often regarded as the father of modern genetics, because although he was not able to identify individual genes, he did demonstrate that a combination of dominant and recessive traits determine the physical appearance of an organism. In the 1950s, research finally revealed that DNA in the chromosomes carried the genetic code of the host organism.
With the confirmation that DNA held the secret to inheritance, people also started charting the genetic code, finding the specific locations on the chromosomes where certain genes appeared. Along the way, they learned a great deal about DNA and inheritance, and the DNA code is continually being studied to identify new genes. Understanding this coding has allowed researchers to manipulate it, removing or altering sections to create a specific desired outcome, such as a crop that is resistant to pests. Knowledge of the human genetic code has also led to gene therapy, in which specific problems are addressed or prevented by manipulating the code of an individual.
The study of this field doesn't just explain the manifestation of physical traits like hair color. Genetics is also used to explore inherited disease, and to determine whether or not people are more susceptible to certain diseases because of their genes. The discipline also involves what happens when things go wrong, as in the case of an organism that inherits an extra chromosome. Some people have also theorized that genes may play a role in behavior, with certain people being predisposed to depression, addiction, and other behavioral issues.