China has a specialized "Anti-trafficking DNA Database," and Zhao Ruihai also suddenly remembered it.
This particular database was established many years ago as a systemic project aimed at rescuing abducted children, finding missing children, and helping shattered families reunite.
Under voluntary circumstances, anyone can enter their DNA data into the "Anti-trafficking DNA Database."
In this way...
When new DNA samples are entered, they can be matched against all existing DNA data in the database, attempting to find pairs that have a blood relationship.
This database project has helped many abducted children find their parents and many parents who've lost their children reunite with them; it is truly full of merit.
The relevant departments also pay great attention to the number of samples in the database. For example, homeless people on the streets and minors engaged in illegal activities... they all assist in entering these "suspect groups'" DNA samples into the database.