To prevent evil spirits from entering the bodies of their male children, parents dressed them in blue. Blue was chosen because it's the color of the sky and was therefore associated with heavenly spirits.
Girls weren't dressed in blue, apparently because people didn't think that evil spirits would bother with them. Eventually, however, girls did get their own color: pink. Pink was chosen because of an old English legend which said that girls were born inside of pink roses. Click here for more weird facts. www.weirdfacts.com