The Big Bang Theory: 10 Things You Completely Missed From Season One

Even though Sheldon Cooper has a gifted scientific mind, his intelligence fails him when it comes to certain rudimentary concepts. Time and time again, he's struggled to understand emotion, empathy, romance, sex, hugging, and sarcasm.

He is also governed by a rigid set of rules and mannerisms which only make sense to him. On top of that, his social skills and ability to read a situation are borderline non-existent. Although the producers have denied that the character has an autism spectrum disorder, Jim Parsons admitted he portrayed the character as a person with Asperger's syndrome.

What's important in this entry though, is that his quirks are inconsistent, especially in the opening episodes. In the pilot, Sheldon has no problem understanding Leonard's sarcastic comments. Despite the fact he's known for referring to sex as "coitus", Sheldon had no qualms using the "s" word in Season 1. He also demonstrated some flirting skills with Penny in the first couple of episodes, when she commented by how impressive his whiteboard is.

But as time went on, these parts of Sheldon's personality were toned down or discarded to make him come across as more innocent and child-like.