It's probably statistical to a certain extent: people of your specific demographic are interested in a certain thing, and you are talking about it the same as all of your peers are, and a statistically significant amount of your peers did Google for it such that now Google assumes that anyone in your demographic will be interested.

Of course that only metas the problem up one level, which is that Google knows enough about you to do this kind of analysis a) on your cohort and b) on you.