1. The kids' hair had to match their parents.

Casting nine characters is a daunting challenge, but creator Sherwood Schwartz was sure of one thing: The kids' locks had to match the hair of the birth parents. Before he cast Robert Reed and Florence Henderson as Mike and Carol, Schwartz had 12 children on reserve, three blonde girls, three brunette boys, three brunette girls and three blond boys. When the parents were cast, the kids whose hair didn't match the parent were dropped.

2. Susan Olsen wasn't blonde enough.

Although Susan Olsen, a.k.a. Cindy Brady, was a blonde in real life, she wasn't blonde enough for producers. To get the perfect complexion, Olsen's hair was bleached regularly. The routine came to a stop when the child's hair started falling out during season two. 

3. Gene Hackman was supposed to be Mike Brady.

Originally, Hackman was tapped to play Mike Brady. When the network caught wind of the casting, they rejected the then-unknown actor and cast Robert Reed instead, who was already under contract with the studio and had some name recognition. We think this worked out all right for Hackman's career, anyways. 

Image: 20th Century Fox

4. Marcia really took a football to the face.

When Christopher Knight couldn't throw the football at the target, producer Lloyd Schwartz said he stepped in and threw a perfect spiral right at Maureen McCormick's nose. 

5. Henderson wore a wig during the first season.

Who knew hair was so important during the first season of The Brady Bunch? Henderson wore a wig during the first season because her hair had been cropped short to appear in the off-Broadway revival of South Pacific. 

6. Poor Tiger.

It's always been a running joke about how Tiger disappeared from the series not long after it started. However, the story is a little more tragic than funny. While filming the episode "Katchoo," Tiger's trainer let the pooch out for exercise. Tragically, a driver accidentally struck and killed the dog.

With more scenes to film, the trainer franctically went to find another dog that resembled Tiger. The new "Tiger" wasn't a very good actor, so producers decided to ditch the dog altogether. 

7. It was never a huge ratings hit.

Despite its popularity today, The Brady Bunch wasn't a ratings hit when it premiered in 1969. In fact, the show never broke the Top 30 in the Nielson ratings. The highest it ever ranked was No. 34. 

8. Schwartz used a clever technique to audition the children.

Having created a few television shows before The Brady Bunch, Schwartz knew a thing or two about casting. When holding auditions for the roles of the children, Schwartz put toys on his desk as a distraction. The kids who didn't glance at the toys and stayed focused during the audition were the ones he figured had the stamina to work on a television show. 

9. The bathroom doesn't have a toilet.

That's right — six kids, one bathroom, no toilet. The network was uneasy about having a toilet on camera, despite the fact Mike and Carol shared a bed. 

10. The back door doesn't have glass.

In order to keep light from reflecting off the glass, the producers removed the glass from the door. Every time you see Alice open the door to call the kids in for dinner, she's really doing more work than she has to. 

11. Henderson had a run-in with 'Star Trek.'

When Henderson arrived late to do her screen test, she couldn't find anyone to do her makeup. Ultimately, she stumbled upon a makeup room for Star Trek, which briefly shared a studio space with The Brady Bunch. Henderson said she sat in a make-up chair between William Shatner and Leonard Nimoy, both of whom ignored her. 

12. The kids don't always sing the theme song

When you think of the theme song, you think of the kids belting out the tune. But initially, a group named the Peppermint Trolley Company recorded the opening theme. Before that, the pop band appeared on Mannix and The Beverly Hillbillies.