The difference is Joe did date his daughter. She had to hide her showers because he'd apparently just opportunistically join her. and she was his daughter, it wasn't a hypothetical "if she weren't my daughter, i'd join her in the shower".
The difference is Joe did date his daughter. She had to hide her showers because he'd apparently just opportunistically join her. and she was his daughter, it wasn't a hypothetical "if she weren't my daughter, i'd join her in the shower".