Doubleclick ad targeting is based on the data collected by the sites you visit, not data Google is collecting about you. DCLK works by the site asking Google for an ad shaped like their idea of you and Google sends them an ad, not by Google knowing what ads you like.

If you're seeing targeted DLCK ads while visiting some site, it's because the site has semantic information on you and has told Google "This user looks like they like puppies; I know this because they read a lot of puppy articles or I have a social media arm and they joined a puppy message group that I manage accounts for. Get that user a puppy ad."

Now, how individual sites track you and unify their concept of your session with their concept of your ad targeting is up to them, but it's worth noting they're allowed to use basically anything (including first-party cookies, browser thumb-printing, and local store API) to do that. They can also share information with other sites (using mechanisms like image bugs to let an affiliated site know you visited their site and what your userID is on their site, so they can compare notes later and build a comprehensive ad profile for you). None of this requires Google's involvement.

Are you sure you're just not predictable? If HN had Ads, you could be blocking all the cookies and analytics you want, but those Ads can "look" targeted.

If the ads are targeted at "Hacker News Viewers", that's one thing. But if a baby crib shows up on HN that's well beyond just "looking" targeted.