Mendelian Heredity
57 objects illustrate this topic:

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Gregor Mendel's garden (#963)
Hair color, black and black (#908)
Hair color, light brown and dark brown (#907)
"Heredity of the eye," 3rd International Eugenics Conference (#1075)
H. Laughlin letter to Walsh, about albinism (#881)
Eugenics: The Science of Human Improvement by Better Breeding, by Charles B. Davenport, multiple pages (#1702)
"Illustrating Mendel's cross of yellow and green peas" (#916)
"Inherited characters in man" (#991)
Jon Alfred Mjøen, director of the Vindern Biological Laboratory (Oslo, Norway) explaining pedigree to children Heljar, Sonja, and Fridtjof (#1580)
"Laws Against Cousin Marriage: Would Eugenicists Alter Them?" (C. Davenport, H. Hunt, and G. Shull), Eugenics: A Journal of Race Betterment (vol II:8) (#1732)
Manuscript of the "Eugenic College of Kantsaywhere," by Francis Galton (title page and page with a definition of "genetic"), multiple pages (#2104)