(Strip Number 456, Original Publication Date, 1 September 1983)
Panel 1: In what's probably a response to Phil telling her that no, he doesn't believe that his parents would treat Elly like filth if she and John lived together with benefit of clergy, Elly reassures him that he gets away with things like this because he's a man.
Panel 2: She then reminds him that he got a bike at a younger age despite her being two years older, he had later curfews and that they laughed off his watering down the vodka because he was a boy. (The implication with that last statement being that if she even touched the liquor cabinet at any point before she left home, she'd get her ass spanked.)
Panel 3: Phil is irritated by her trying to get him to see a point he'd rather not: they were stricter on her because she was a girl and that he had a free ride 'cause he has a Y chromosome.
Panel 4: His response is to snarl "I dunno, Sis. You always managed to make up for it."
Summary: Phil seems to be talking about the way she treats him now: like a child who needs to be brought under control for his own good and totally not as a means of exacting petty revenge for something that only became a problem because he was there to highlight it. If she were an only child, she would probably simply have accepted getting a bike later, early curfews and having her sex life policed so that the neighbors don't talk; it's only because he exists that the oblivious clod sees the imbalance which she wishes him to answer for.