Gregor Mendel was fortunate to have chosen some of the most genetically simple of characters in the garden pea for his seminal experiments that laid the foundation for the science of genetics. Each was determined by a single gene on a different chromosome, and each trait behaved as clearly dominant or recessive in this experimental system. This allowed Mendel to recognize patterns of heredity, which are described as the law of segregation of alleles, and the law of independent assortment. In its broadest sense, non-Mendelian inheritance includes any hereditary phenomena that do not appear to conform to Mendel's laws or to be attributable to single autosomal genes. It is not a clearly-defined classification, and is used quite variably in the scientific literature.

Arguably, the first form of non-Mendelian inheritance to be recognized was sex-linked, since Mendel studied only autosomal characters; however, this is rarely cited as...