Heredity is the mechanism by which characteristics, resemblances, and differences are passed down from one generation to the next. It is also called inheritance or biological inheritance. Gene is the unit of heredity. Genetics is the study of heredity in biology. Heredity refers to the transmission of characters or traits from parents to their offspring. It is the continuity of features from one generation to another. Genes are the functional units of heredity that transfer characteristics from parents to offspring. Sexual reproduction involves two individuals, one male and one female, who produce sex cells or gametes that fuse to form a new organism. The three laws of inheritance proposed by Gregor Mendel are the Law of dominance, the law of segregation, and the law of independent assortment. The transfer of traits from one generation to the next is termed heredity. The basic concepts of heredity, derived by Gregor Mendel during his studies in the mid-19th-century, became the foundation for the modern science of genetics.