Goose was born in Coastline. There was absolutely nothing special about her. Once her parents even missed her trying to pick her up from kindergarten because they forgot what she looked like. Goose grew up playing and gossiping with other girls, reading the most popular books (mostly trashy romance), writing silly love letters to her crushes (there were a lot of them and if you showed adult-Goose those letters she would die from internal bleeding), and trying on her mom's makeup (which she still does because she can't afford to buy her own).
She got a crappy score in her college entrance exam and went to a random college in the middle of nowhere (note: it was western Bauhinia). She graduated, knowing absolutely nothing about what she was going to do with her life, and went back to Coastline to her parents. (She even forgot what her major was.) She got a job as a janitor in a random office building, got fired for being dumb; worked as a waitress, got fired for being lazy; and for quite a while refused to leave her room.
One day, she saw a military recruitment ad. She was like, "wow that's really cool" and went to the nearest office. She almost didn't make the cut, but she did.
After serving two years in the navy, she got recruited into the MSS. Her assigned shifu was Paperweight. During the same year, Pumpkin was also recruited from the army as Halcyon's apprentice. They got assigned together as a team.