Early life

Greg Sanders grew up in San Gabriel, California. Although friends and family told him that science was for geeks, Greg knew from a young age that he wanted to become a scientist. The season 4 episode "Coming of Rage" revealed that he had a palate expander, braces, a retainer, and head gear while growing up. Although he was never good at sports, Greg was the captain of the high school chess team. In the season seven episode "Fannysmackin'", Greg reveals that his overprotective mother refused to let him play sports in high school because he was her only child. Greg stated that his mother wanted four children, but only got one. In the same episode, he reveals a fondness for Doc Martens in high school and thinks that skinheads' enthusiasm for that style "kinda ruined it for everyone." At some stage, Greg lived in New York (season 2, "Burked")

Education

Greg successfully managed to juggle studying and extra-curriculars and eventually went on to earn his degree in chemistry from Stanford University, where he graduated Phi Beta Kappa. He has a wide variety of hobbies, including surfing, scuba diving, and numismatics (the study of money/coins and currency - in the episode "Precious Metal" his knowledge of the subject helps the investigation). In "Precious Metal" it is also revealed that Greg likes supermodels and latex.

He is fairly well read, being familiar with The Tell-Tale Heart by Edgar Allan Poe. However, he also contradicts his scientific training and believes in occultism, mostly due to lineage, as his grandmother was a psychic herself.

Professional life

Greg could be considered the most "normal" member of the CSI team. He's always smiling, he remains somewhat optimistic and he maintains a lot of interests aside from his Crime Lab work (he listens to Marilyn Manson while running lab machines and hides porn magazines in some area cabinets). This is most likely due to his youth; he hasn't been fully subjected to the horrors of this job like the rest of the team. He is also not concerned with the financial aspect of a job -- just the joy that it brings.

In the season 3 episode "Play with Fire" he was involved in a lab explosion, which he survived. Also, in the season 7 episode "Fannysmackin'" he is severely injured after he risks his life to save a tourist being beaten to death by a gang of teenage thrill seekers. He later tells Gil Grissom that he has kept his promotion to CSI a secret from his parents because he didn't want to worry them. Grissom tells Greg his mother will be proud of him for saving a man's life. In the season 7 episode "Post Mortem", Greg's split-second decision to run over one of the men threatening the tourist is found to be "excusable." The man's family disagrees with the verdict and serves Greg with a civil suit. In "Empty Eyes" Grissom informs Greg that the city of Las Vegas has settled the civil suit with the family, which has received millions. In a later episode, "Big Shots" the dead man's brother is implicated in a murder investigation, but Greg asks the prosecutor to be lenient with him. Greg appears to feel sympathy for the man's mother, who shouts at Greg that he "owes her" for the death of her first son and her second son is all she has left.

Greg has arguably had the greatest level of character development of all the CSI charatcers. He started out as the resident lab rat, sitting quietly in his lab working away on the loads of evidence and DNA the CSIs brought in, usually responsible for making discoveries about pieces of evidence that would crack a case open. Eventually Greg grew tired of the lab and longed for a position out in the field. He failed his first test when he urinated in a toilet at a crime scene ("Viva Las Vegas"), but eventually attained the rank of CSI Level One ("Who Shot Sherlock?"). At his low rank, he mostly only assists at crime scenes, collecting evidence and helping the more experienced CSIs. He rarely interviews suspects. However, he later graduated to investigating crime scenes on his own. In the season seven episode "Fannysmackin'" Greg celebrated over dinner with the female district attorney after his testimony at a jury trial helped put away a criminal. David Hodges' character has been somewhat expanded since Greg's promotion, and he now seems to fill the role of lab rat on the show that Greg once held.

Early on in the show, Greg had a huge crush on Sara Sidle, which may or may not have disappeared. Sara doesn't like Greg romantically; she appears to only have eyes for Gil Grissom. Nonetheless the two remain close friends, as Sara was Greg's mentor through his training and continues to offer him helpful hints. But along with his co-workers, he was shocked and speechless when Grissom revealed his relationship with Sara Sidle as she is missing. ("Living Doll") This could mean that he still has feelings for her.

Greg is also notable for his ever-changing hairstyles.

Family

Greg is part Norwegian, which was revealed in season 3, episode 3 ("Let the Seller Beware"):

Grissom: Your mother's maiden name is Hojem, correct? Hojem is Norwegian?

Greg: Yeah. And you know, my grandfather got tossed from Norway for getting my grandmother pregnant before they got married. To this day, he still tells me "som man reder, så ligger man".

(pause)

Greg: One must lie in the bed one has made.

His heritage was referenced again in season 5, episode 5 ("Swap Meet"):

Hodges: Good thing you don't have to pass a spelling test to work in the field. 'Funtain' water?

Greg: My people are Norwegian. That's how we spell it.

(Note: Fountain in Norwegian is "fontene".)

Greg has mentioned on several occasions his grandfather, whom he affectionately calls 'Papa Olaf.' He also mentions his Nana Olaf in season 6, episode 19 ("Spellbound"). She apparently possessed psychic powers, and his family believes that Greg may have inherited this ability from her.