It reminds me of how there is a gene that determines whether eating asparagus makes your pee stink, and there’s a different gene that determines whether you can smell it. I had a friend who didn’t have the stinky pee gene, but her boyfriend did, and she complained of the smell when she used the bathroom after him occasionally. He had the stinky pee gene, but not the gene to be able to smell the stink.

This came up in a random conversation with my friend, before she knew about the genes thing. I was so excited that I got to tell her about a cool science thing that I couldn’t speak for a few moments.