Lisa was Finn's foster father's ex-partner, who has always secretly had a crush on Finn. According to her, Finn used to masturbate to topless images of her that he hid under his mattress as a teenager. Finn always believed his foster dad, Mike, was his biological father, but after receiving fellatio from Lisa, Mike revealed to Finn that he was not his real father out of disappointment and anger. This, therefore, means Finn has barely any relation to Lisa.