Maybe opt out, if you see an offer for a "free health check" the next time you're in China...
"Mr. Imin was one of millions of people caught up in a vast Chinese campaign of surveillance and oppression. To give it teeth, the Chinese authorities are collecting DNA — and they got unlikely corporate and academic help from the United States to do it.China Uses DNA to Track Its People, With the Help of American Expertise | NYT
China wants to make the country’s Uighurs, a predominantly Muslim ethnic group, more subservient to the Communist Party. It has detained up to a million people in what China calls “re-education” camps, drawing condemnation from human rights groups and a threat of sanctions from the Trump administration.
Collecting genetic material is a key part of China’s campaign, according to human rights groups and Uighur activists. They say a comprehensive DNA database could be used to chase down any Uighurs who resist conforming to the campaign."