Asparagus Piss

apparently there are two things at work here. you either have or don't have the gene that makes your wee smell funny after you eat asparagus. separate to that, you either have or don't have the gene that allows you to smell the funny wee smell. the evolutionary advantage of this escapes me, but there you go.

True - I can smell my wife's asparagus piss, but she remains olfactorily oblivious.