Log into your Facebook account on a desktop and head to this page. Here, you'll see all of your so-called "ad preferences," divided up by interest category like News and Entertainment, Business and Industry, People, etc. These include both specific pages you've liked and broader categories of things Facebook thinks you're into based on every click, scroll, and hover you've made in your Newsfeed.
Scroll down and click on the "Your Information" tab and tap on "Your categories." Here, you'll see things about you "based on information you've provided on Facebook and other activity." Likely, you'll see some fairly innocuous intel about your birth month, the type of email provider you use, and the model of mobile device you primarily use. You'll also notice a grey box labeled US Politics. Are you the Very Liberal, Moderate, or Conservative it's ascribed you to be? Even if you've never liked a particular candidate's page, or even a politically charged post of any sort, Facebook tries to predict your personal feelings by gauging the self-professed political identities of people who like the same pages that you do, and lumping you in with them.