There will be a group of people who legally are not allowed to enter one or more of the US, EU, or China because of genetics or biology via laws or regulations.

For example, China passes a law saying cloned humans aren't allowed to enter, and there are at least ten clones. Or the EU passes a law saying passive carriers of some disease risk or genetic state can't enter.

Or the US says people who have had some type of CRISP can't enter.