In January 1990, John Winchester met Kate Milligan in Windom, Minnesota when he came into the hospital where she worked as a nurse when he was injured in a hunt. Their son, Adam Milligan, was born on September 29, 1990. Throughout Adam's childhood, John rarely contacted Kate and their son, so much so that the first time Adam met his father was when he was twelve years old. Despite all of this, John taught Adam how to play pool and poker, brought him to baseball games on his birthday, bought him his first beer when he was 15, and even taught him to drive The Impala.
Kate and Adam were killed by ghouls as revenge for the killing of their parent by John Winchester during the time John and Kate met. One of the ghouls took on Adam's form and memories in order to lure Sam and Dean to the town and later teamed up with its sibling in the form of Kate to finish them off. Both ghouls were killed by Sam and Dean.