https://www.youtube.com/watch?v=UUXIleMghSI (21:28)
China’s national Y-STR database
In 2003, China’s Ministry of Public Security established a national DNA database for police forensic work.12 Over the following decade, police collected DNA samples during criminal investigations.
However, by the early 2010s, Chinese authorities began to engage in the mass collection of DNA from even wider groups. This included not only programs in Tibet and Xinjiang, which were the first to start, but also more targeted efforts elsewhere. Between 2014 and 2016, the Public Security Bureau of Henan Province collected DNA samples from 5.3 million men, or roughly 10% of the province’s male population.13 The province’s police saw the project as a massive improvement in their ability to conduct forensic investigations and extend state surveillance over even more of Henan’s population.
The success of that project encouraged its expansion nationwide and, on 9 November 2017, the Ministry of Public Security held a meeting in Henan’s provincial capital, Zhengzhou, calling for the construction of a nationwide Y-STR database (Figure 4).14
Data collection quickly expanded across the country. Between November 2017 and April 2020, documented instances of police-led Y-STR sample collection have been found in 22 of China’s 31 administrative regions (excluding Hong Kong and Macau) and in more than a hundred municipalities.15
Those are only the instances for which we have direct evidence. Given the national scope of this program, these figures are certainly an underestimate.
Unlike autosomal STR data, which is present in the DNA of both males and females, Y-STRs (the short tandem repeats on Y chromosomes) are found only in male DNA.16 Passed directly from father to son, they aren’t recombined with every successive generation. There’s therefore little variation in Y-STRs, apart from random mutations, and the Y-STR profile of a man will be nearly identical to that of his patrilineal male blood relatives. This means that forensic traces drawn from Y-STR data can point only to a genetically related group of men and not to an individual man.
However, when combined with accurate genealogical records (family trees) and powerful next-generation gene sequencers,17 Y-STR analysis can be a powerful tool. Because surnames are usually inherited from fathers, men who share a common surname are likely to share a common paternal ancestor and a common Y-STR profile.18 Likewise, if the Y-STR profiles of two men match, their surnames are likely to match, too. Therefore, if a Y-STR database contains a large representative sample of DNA profiles and corresponding family records, even an unknown male’s data can potentially be matched to a family name and even an individual, so long as investigators have on file the Y-STR data of that male’s father, uncle or even third cousin (Figure 5).
For the Chinese Government, Y-STR analysis presents a more cost-effective and efficient method of building a national genetic panopticon. Unlike in Tibet and Xinjiang, authorities don’t need to collect DNA samples from all Chinese citizens in order to dramatically increase their genomic surveillance capacity. Authorities in Henan achieved 98.71% genetic coverage of the province’s total male population by collecting Y-STR samples from 10% of the province’s men and developing family trees for nearly all of the province’s patrilineal families.19 Following a similar program nationally, Chinese authorities could achieve genetic coverage for nearly all men and boys in China.
