Reading this, it's exceptionally confusing as to how many family members you're talking about exactly; Your use of they, them, their is causing me to imagine some microbiome obsessed tribe has moved in and is holding conferences on it in your kitchen...
No I found it readable though I can understand why they might be confused a little bit too but its nothing to worry about in my opinion.
Honestly regarding your anecdote and the gourmet syndrome the title itself, I don't really have nothing to add except I guess just note that human mind truly just works in remarkable ways.
But each day science uncovers more and more secrets about our brains. Maybe one day the gourmat syndrome or (your anecdote [if its a syndrome? or anything more observed or who knows, I am not sure as I don't have much medical knowledge being honest] might be explained in future too by future science advancements and scientists)
It's crazy how far we have come in medical science and (also not) [but I don't mean it in a bad way] at the same time.
Singular they/them is mostly only a problem to non-native speakers. It's a pretty uniquely English thing to blur the singular and plural, at least among languages that use pronouns much.
