Google, Facebook, Twitter, and almost every website or app that you use does the same. That's why you can casually look at a pair of pants that catch your eye in a random ad, and after that you will get bombarded by ads for that same thing. Mention to your friend that you are looking for a puppy, suddenly you're inundated with PetSmart and Petco ads. That is how the internet works.
If you don't want the apps and such to suggest things for you, don't accept cookies, don't give the apps permission to access your contacts and media files. Don't give the apps permission to access the location services (GPS) on your phone.
Stop scaring old folks.