How does google know???

I love google but I'm getting a creepy big brother vibe from them. I have been dealing with my dog being infested with tics thanks to a stray getting in our yard. I have not posted this info ANYWHERE on the internet because, really, who needs to know my dog has tics, right? So today I'm looking at my blog and what is google adsense avertising?? Tic dipping products!!! I am totally freaked out now! LOL