Sibling piety.
I have an older sister who is quite religious. Neither Mrs Miasma or I are among the faithful. My sister knows this but whenever we'd visit for dinner, hands were held and grace was always said. She'd usually find a way to remind me that she wouldn't ask me to say the blessing because she knew I didn't know any.
I always wanted to memorize this hymn so I could sing the blessing the next time we have dinner together.