The stars of "The Big Bang Theory" have shared their childhood photos on Instagram. Jim Parsons, who played Sheldon, had a typical 70s look with big hair and an orange sweater. Melissa Rauch (Bernadette) showed off a very fashionable 80s look, while Mayim Bialik (Amy) looked happy in a photo from her childhood.

Johnny Galecki (Leonard) could be seen posing at Niagara Falls, and Kaley Cuoco (Penny) was pictured with her little sister. Finally, Kunal Nayyar (Raj) sported a classic red all-in-one outfit from the early 80s. These photos provide a glimpse into the childhoods of the beloved characters who went on to star in one of the biggest sitcoms of all time.