I work in advertising (check my post history). Likely this is just "household extension". How it works: 1. You visit my website on your phone 2. I can now sen

I work in advertising (check my post history). Likely this is just "household extension". How it works: 1. You visit my website on your phone 2. I can now send ads to your phone, but not your desktop 3. I enable cross-device targeting 4. I can now send ads to your phone, laptop, and work computer 5. I enable household extension 6. I can now send ads to any device associated with your household (your girlfriend's phone and laptop, your son's tablet, etc.) The more likely explanation (for the kung fu stuff) is just random chance. You get like 500 ads a day, so some of those will coincidentally line up with things you've recently done. But your behavior (watching a kung fu movie) might have gotten you or your household added to a 3rd party audience for interest in karate, and then you get karate ads. Same for open houses - there are data providers who sell the audience "user has been to an open house recently" or more likely just "in-market for real estate services"