What data is enough to identify a unique person, and why?

It also shows clearly why it is possible to learn many things about a person (for instance, sexual orientation) from a few "what do you like" questions.

In regard to the case of trying to learn about movie preference associations from crowdsourcing, identifying a person from a data base that lists which movies each person has watched seems to be possible only if you know some set of movies the target person has watched. But I think that if you don't have a way of getting that starting data about a person, it is impossible to identify anyone.

US citizens: call on the US to condemn the genocide of Rohingyas.

US citizens: call for medical insurance to cover birth control.

The European Union is getting ready to fight hard against tax dodging through tax havens.

The Prime Minister of the UK is fighting to perpetuate tax dodging. Perhaps partly because her husband works selling tax dodging schemes.

The Houthis and the supporters of former president Saleh, who used to be allies, are now fighting each other.