Mendelian inheritance is a set of rules about genetic inheritance.
The basic rules of genetics were first discovered by a monk named Gregor Mendel in the 1850s, and published in 1866. For thousands of years, people had noticed how traits are inherited from parents to their children. However, Mendel's work was different because he did experiments on plants, and designed those experiments very carefully.[1]
In his experiments, Mendel studied how traits were passed on in pea plants. He started his crosses with plants that bred true, and counted characters that were either/or in nature (either tall or short). He bred large numbers of plants, and expressed his results numerically. He used test crosses to reveal the presence and proportion of recessive characters.
Mendel's laws apply widely, but not to all living things. They apply to any organism which is diploid (has two paired sets of chromosomes) and which engages in sexual reproduction. They would not apply to bacteria, for example, or to asexual reproduction. They do apply to the great majority of plants and animals.
Mendel explained the results of his experiment using two scientific laws:[2]
Mendel's laws explained the results he got with his pea plants. Later, geneticists discovered that his laws were also true for other living things, even humans. Mendel's findings from his work on the garden pea plants helped to establish the field of genetics. His contributions were not limited to the basic rules that he discovered. Mendel's care towards controlling experiment conditions along with his attention to his numerical results set a standard for future experiments.[4]
![]() (1) Parental generation. (2) F1 generation. (3) F2 generation. Dominant (red) and recessive (white) phenotype look alike in the F1 generation and show a 3:1 ratio in the F2 generation |
![]() (1) Parental generation. (2) F1 generation. (3) F2 generation. The "red" and "white" allele together make a "pink" phenotype, resulting in a 1:2:1 ratio of red:pink:white in the F2 generation. |