Mendel was born in Silesia in the Austrian Empire, his parents were horticulturalists, which gave Mendel more opportunities to contact plants during daily life. Mendel's most famous experiment was the "Mendelian pea hybridization experiment," which led to theories that underpin today's genetics. He is the founder of modern genetics, so he is called the "father of modern genetics".
Mendelian chose to study the inheritance of Pisum sativum in the "Mendelian Cross Experiment". He chose peas because peas are strictly self-pollinating, closed-flowering plants. So the offspring of peas are purebred, which makes the results of hybrid experiments reliable. Also, these traits in peas were stably passed onto offspring. Crosses between pea varieties with these easily distinguishable and stable traits make the experimental results easier to observe and analyze.
During the experiment, He used purebred tall and dwarf peas as parents and cross-pollinated their different plants. It was found that the first-generation plants (indicated by F1) obtained from their crosses showed tall stems whether they used tall stems as the female parent, short stems as the male parent, or vice versa. Therefore, as far as this pair of relative traits is concerned, the trait of F1 plants can only show the trait of one parent—high stem, while the trait of the other parent—dwarf stem is not shown in F1.
In the above experiment, since only one of the relative traits（the dominant trait） is shown in the hybrid F1, then, does the other trait in the relative trait ( the recessive trait ) disappear? With such doubts, Mendel continued his hybridization experiments. Mendel self-pollinated F1 tall peas, and then sowed the resulting F2 pea seeds the following year to obtain hybrid F2 pea plants, resulting in two types: one is tall peas ( Dominant trait), one is short-stemmed pea (recessive trait), that is: two different manifestations of a pair of opposing traits - both tall and short-stemmed traits are expressed. Mendel's doubts were lifted, and he called this phenomenon “the phenomenon of separation”.
In F2, the relative traits of the hybrid parents—dominant traits and recessive traits—are displayed again, which is “the phenomenon of trait segregation”. It can be seen that the recessive traits did not disappear in F1, but were temporarily covered and could not be expressed.
In 1866, Mendel published his thesis "Experiments on Plant Hybridization". In it, he proposed that inheritance is the result of each parent passing on a factor for each trait. If the factor is dominant, it will be expressed in offspring. If the factor is recessive, it will not appear, but will continue to be passed on to the next generation. Each factor acts independently of the others, and they do not mix.