Consider public IP addresses. Geolocation can link an IP address to a region as imprecise to a country to a more precise region such as a city. Combining rough location to a few other data points can greatly narrow down meatspace candidates for a particular account [1]:

> According to one landmark study, these three characteristics are enough to uniquely identify 87% of the U.S. population. A different study showed that 63% of the U.S. population can be uniquely identified from these three facts.

If you have a significant online presence, your gender or age might be revealed by the way other users address you on some website. If a website happens to collect gender or birthday, then the website might share/sell the info to data brokers.

If police manage to narrow down the location of a potentially incriminating online action to a household, then the police could physically show up with a warrant and ask about who was using which computer in the house at that time.

[1] https://www.eff.org/deeplinks/2023/11/debunking-myth-anonymo...