What is Mendelian inheritance?
'''Mendelian inheritance''' is a set of rules about [[genetics|genetic inheritance]]. [[Image:Gregor Mendel.png|thumb|right|150px|Gregor Mendel, father of modern genetics.]] 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 [[Trait (biology)|traits]] are inherited from parents to their children. However, Mendel's work was different because he did [[experiment]]s on [[plant]]s, and designed those experiments very carefully.<ref>Weiling F. 1991. Historical study: Johann Gregor Mendel 1822–1884. ''American Journal of Medical Genetics'' '''40''', 1–25</ref> 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. == Mendelian genetics == === Limitations === 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's laws === Mendel explained the results of his experiment using two [[scientific law]]s:<ref>Stern, Curt and Sherwood, Eva R. (eds) 1966. ''The origin of genetics: a Mendel source book''. Freeman, S.F.</ref> * '''1'''. Factors, later called [[gene]]s, normally occur in pairs in ordinary body cells, yet separate during the formation of sex cells. This happens in [[meiosis]], the production of [[gamete]]s. Of each pair of [[chromosome]]s, a gamete only gets one. <br/>The factors (genes) determine the organism's [[Trait (biology)|traits]], and are inherited from its parents. As the pair