Michael is the only child of Gina Tribbiani, for the first 21 years of his life he had no idea who his father was. Michael is intellectually brilliant, obvious MIT-material, responsible, and considerate. However, he majorly lacks social skills (confidence especially) and is a 'nerd' who is not popular with girls.
Joey, Season 1
When Joey moved to LA Michael jumped at the opportunity to move out of his mothers house after 20 years. By living with Joey Michael hopes to gain skills for picking up women. Michael's inability to notice women is shown in "Joey and the Fancy Sister", in which he is completely oblivious to a girl who likes him.
In "Joey and the Road Trip" it is revealed that Michael goes to Vegas and counts cards, this however stops at the end of the episode when he is caught out.
Throughout this season, Joey's agent, Bobby, had a fascination with Michael, this is put to a stop by Gina in the season finale.
Joey, Season 2
Michael is the only son of Gina Tribbiani and Jimmy Costa. Michael is very close with his uncle Joey and see's him as an inspiration when it comes to picking up women. Michael doesn't seem to have a close relationship with his Aunts, evidenced by the fact that he can never figure out which Tribbiani girl is which ("Joey and the Fancy Sister"). Michael appears to have a happy relationship with his grandfather.
Due to Michael personality and lack of confidence Michael has had very little female relationships. Michael dated Joey's script editor, Chris, for a while to whom he first had sex with.
Michael is self-conscious that he has been so sheltered and that his mother, Gina, breast fed him until he was seven. He is a huge Star Trek: The Next Generation and Star Wars fan. He is extremely intelligent, an aerospace engineer, attends Caltech and specializes in applied thermodynamics, works with his rival Seth frequently on engineering projects, and is an obvious direct opposite from his more street-wise mother and uncle.
Michael idolizes his Uncle Joey's ability to date many women, and who himself is sheltered and nervous around girls.
Michael's age was first defined by Joey in the first episode.
His age throughout the series was; 1 (20-21), 2 (21-22)
Michael was 20 years old throughout series 1. He was 21 in series 2 until Jimmy Costa and Gina decided to move in together. Jimmy was complaining about Michael's needs. Michael later stated that it was his birthday, meaning that he was at this point, 22.
- Michael is very weak. In the episode "Joey and the Wrong Name", he could not do a real push-up or a real chin-up and he only beat Joey in an arm wrestle with two hands and still he had trouble doing it.