Matt is usually a quiet person, he has always been like that since he was little. He first phased into a wolf when he was only 14 years old, but because there was nobody that could explain to him about what he was going through, he became a lot more quiet that he had ever been before. Fortunately Matt is a calm person, so he was able to control his emotion most of the time, and this works to his advantage because he doesn't have to worry about inadvertently phasing into a wolf.
Matt shares the same great-great-grandfather from his father's side of the family with Jared Cameron, a member of Sam Uley's pack.
Matt's mother was not a member of the Quileute tribe, but she moved into the Quileute's reservation with Matt's father when she married him. Unfortunately Matt's mother died because of an illness when Matt was very young, and so Matt grew up without a mother.
Matt's relationship with his father is at worse can be describe as a neutral relationship. Since matt has always been a quiet person, he never really bonded with his father while he was growing up. Even so, Matt and his father somehow enjoyed their life living together since they both never meddle with each other business.
A problem emerged when Matt phased for the first time when he was 14 years old. He didn't know what had happened, and since he had never been close to his own father, he didn't have anyone to talk to about his phasing. Fortunately Matt was able to control his emotion, and therefore he was able to learn pretty quickly how to control when he'd phased into a wolf. Since the first time he phased, there was only one time that he ever phased into a wolf inadvertently. It was when he saw that the girl he liked went for a date with another boy. Even then he was still able to control his mind and so he ran into the woods to avoid attacking the girl and her date out of sheer jealousy.
When Matt was 18 years old, he went out into the woods in his wolf form just to have some fun, since he secretly enjoyed the sensation of exploring the woods in his wolf form. When he was put exploring, he stumbled upon Sam Uley. They both phased back into their human form, and Sam finally became the person that explained to Matt about his ability to shapeshift into a wolf.
Sam then offered Matt to join his pack, but Matt said that he'd think about it. He's been living his existense as a 'lone wolf' of sorts for four years, and he somehow enjoyed the occational solitude that his wolf-form afford him. Understanding Matt's point of view, Sam concluded his explanation by warning Matt that since he's not a member of Sam's pack, then Matt won't be able to comunicate telepathically with members of Sam's pack. So Sam suggested to Matt, that if ever Matt stumbled upon other members of Sam's pack he should phase back into his human form to show that he means no harm toward that wolf.