Atopy is a predisposition toward developing certain allergic hypersensitivity reactions. Atopy may have a hereditary component, although contact with the allergen or irritant must occur before the hypersensitivity reaction can develop.
As of 2012, 63.9 percent of players playing in Major League Baseball are white. There is no way of telling the exact number due to the number of players.
Jackie Robinson was the first African American MLB player. Jackie Robinson is credited with breaking MLB's color barrier in 1947. However, back in 1884 in the American Association, a major league at the time, Moses Walker and his brother Welday Walker played for the Toledo Blue Stockings. Moses was nicknamed Fleet and played 42 games as a catcher and batted .263.