Hair Color Was Essential to Casting
When it came to casting, the parents didn’t come first. According to ABC, the producer and his son Lloyd Schwartz explained in ‘Brady, Brady: The Complete Story of the Brady Bunch from the Father/Son Team Who Really Know,’ that it was actually the kids who were chosen first.
The show writers knew that they wanted the mom’s kids and the dad’s kids to have contrasting hair colors, but they didn’t know who they would cast as the parents yet. The show ended up choosing 12 potential Brady kids, and once they knew who was playing the mom and dad, they picked the kids with their TV parent’s hair color.