Gregor Mendel is called the father of genetics, because he introduced various terms such as gene, heredity, offspring, parental generation etc. The three primary sources that were important for Mendelian genetics are Cross pollination: Due to this the traits of different plants can be introduced in the offspring. Plants differing in one character because of which if there was any change in the character of the plant it was easily noticeable. The dominant and recessive phenotypes which are responsible to determine which trait will be shown by the plants. These 3 are the primary sources of mendelian genetics. Solution Gregor Mendel is called the father of genetics, because he introduced various terms such as gene, heredity, offspring, parental generation etc. The three primary sources that were important for Mendelian genetics are Cross pollination: Due to this the traits of different plants can be introduced in the offspring. Plants differing in one character because of which if there was any change in the character of the plant it was easily noticeable. The dominant and recessive phenotypes which are responsible to determine which trait will be shown by the plants. These 3 are the primary sources of mendelian genetics..