Dr. Sheldon Lee Cooper (Jim Parsons) is a theoretical physicist, possessing a Bachelor of Science, Master of Science, PhD, an ScD, and an IQ of 187. Originally from East Texas, he was a child prodigy, starting college at the age of 11, and receiving his PhD at age 16. He is cold and calculating, and refrains from any form of physical contact if possible. Sheldon exhibits a strict adherence to routine to the point of exhibiting obsessive–compulsive personality disorder, performing specific activities on specific days and specific times, such as doing the laundry on Saturday night at 8:15. Any disruption to this routine distresses him enormously. A running gag has him always knocking on doors or other surfaces in a pattern of three knocks and one call repeated three times, which he has to complete no matter what. He has forced Leonard into signing an absurdly exhaustive "Roommate Agreement", and later enters a similar "Relationship Agreement" with Amy Farrah Fowler. Sheldon has great difficulty identifying sarcasm and irony and responding in kind, and a recurring topic is his efforts to acquire these skills. He has also enormous difficulties lying or even keeping a secret, giving himself away with wild facial tics and implausible statements. He is however fond of occasionally playing a prank, which he typically punctuates with his trademark exclamation "Bazinga!". Sheldon has a superiority complex and makes no effort to hide his contempt for other people's intellects, often making highly inappropriate comments. A common joke is his inability to drive, although he did receive a learner's permit.[3] Sheldon loves comic books and science fiction like his friends, but to the point of being obsessed about them, and is a fan of Spock, a fictional character of the Star Trek franchise.[4] Unlike Leonard and Raj who come from intellectual families, Sheldon stands out from his own relatives. His father, George, whose death pre-dates the series, was described as a stereotypical Texan who liked football, skeet shooting, and heavy drinking,[5][6] his mother, Mary, is a devout Evangelical Christian, who does not possess anything near Sheldon's intellect (though she displays a great deal of common sense);[7] his twin sister, Missy, and as-yet unseen brother, George Jr., were both described by Mary as being "dumb as soup". His fraternal twin sister who later has a baby boy makes Sheldon an uncle. He meets Amy Farrah Fowler in the Season 3 finale and starts a highly unusual and very slowly evolving relationship with her and by season 7 they having started kissing each other. Previous to this, he has also exhibited some affinities with Leonard's equally unemotional mother.