Word that means "tendency to avoid something"

Solution 1:

disinclination might fit. It covers both unwillingness and a mild aversion so you tend to avoid that thing. It does not suggest a strong dislike also.

• a lack of inclination; a mild aversion or reluctance.

• that toward which you are inclined to feel dislike

Solution 2:

Aversion is an acceptable word for this. Read definition number 3.

Aversion is a strong dislike, but it carries a sense of repellence, too. Per Merriam-Webster: It is a tendency to extinguish a behavior or to avoid a thing or situation and especially a usually pleasurable one because it is or has been associated with a noxious stimulus.

I think this sounds exactly like the word you are requesting.

You can absolutely have an aversion to PB&Js.