Genetics is the study of units of heredity. These are called genes, and they determine almost everything about what makes you, you. Genes are passed from parent to offspring. Because genes have a strong influence on all organisms, genetics is a very broad scientific discipline, touching on fields like biochemistry, medicine, and evolution.

The “father of genetics” is Gregor Mendel. In the mid-1800s, Mendel, an Austrian monk, studied how genes were inherited in pea plants. By cross breeding over thirty thousand pea plants, Mendel discovered patterns in how their characteristics, or traits, are passed from generation to generation.

By the 1940s, technology had become advanced enough that scientists were able to study the gene itself—that genes were made of DNA, and this DNA is carried in structures called chromosomes. These chromosomes then determine which traits are seen in the next generation. By 1953, a pair of scientists named James Watson and Francis Crick had discovered the structure of DNA. Today, scientists called molecular biologists study specific sequences in DNA, and apply what they learn to everything from making medicines and treating illness to growing different kinds of crops that resist drought and disease.

Because genes are passed from parent to offspring, they also have a huge effect on how a population of organisms change over time. Scientists in the field of population genetics study how changes in genes affect organisms over many generations, as well as how they help living creatures adapt to their environments.

Genetics encompasses everything from the building blocks of DNA to how populations evolve. It’s an important field, and will remain so as we continue to explore how genes influence not only us, but all life on earth.