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.
Certainly, the 25-man rosters of the 30 major league teams are diverse in other ways. Players of Latin descent made up 28.2 of players on MLB rosters at the start of the 2013 season. But a sharper, ground level view of diversity in sports may explain the 8.3 percent. The baseball landscape has changed in America since the days of Robinson, particularly the landscape of the backyard and the sandlot.