Genetics is the branch of biology concerned with the study of genes, genetic variation, and heredity in organisms. It explores how traits are passed from parents to offspring and how the genetic makeup of populations changes over time. At the molecular level, genetics investigates the structure and function of genes (segments of DNA), how they are regulated, and how they guide the production of proteins that determine an organism's phenotype.
The modern science of genetics began in the mid-19th century with the work of Gregor Mendel, an Augustinian friar who studied trait inheritance in pea plants. His discovery of the laws of segregation and independent assortment laid the foundation for the field. In the 20th century, the rediscovery of Mendel's work, combined with the discovery of the DNA double helix by Watson, Crick, Franklin, and Wilkins in 1953, launched the era of molecular genetics.
Genetics has revolutionized medicine, agriculture, and our understanding of life history. It has led to the development of genetic screening for hereditary diseases, personalized medicine, and gene therapies. In agriculture, it has enabled the breeding of high-yield and disease-resistant crops. The sequencing of the human genome and other organisms has opened new frontiers in evolutionary biology and biotechnology, raising profound ethical questions about genetic engineering and cloning.