Speaking of good writing, I really like how realistic the childhood flashback is. Parents out there, don't ever use unclear language with small children: if you tell them "say it again" as a dare, in the way you would an adult, they take it at face value, and will go through a lot of pain learning to interpret mixed signals, which may lead to their becoming distrustful of you. Until they know how to interpret tones of voice and innuendo, prioritise clarity.
Not that I'm saying this was the sperm donor's mistake here. His mistake is not throwing himself off a cliff the moment it became clear what a piece of shit he is.