"The Simpsons" uses a floating timeline in which the characters never physically age, and, as such, the show is generally assumed to be always set in the current year. Nevertheless, in several episodes, events in Homer's life have been linked to specific time periods. "Mother Simpson" (season seven, 1995) depicts Homer's mother, Mona, as a radical who went into hiding in 1969 following a run-in with the law; "The Way We Was" (season two, 1991) shows Homer falling in love with Marge Bouvier as a senior at Springfield High School in 1974; and "I Married Marge" (season three, 1991) implies that Marge became pregnant with Bart in 1980. However, the episode "That '90s Show" (season 19, 2008) contradicted much of this backstory, portraying Homer and Marge as a twentysomething childless couple in the early 1990s.