Just from the tech we know they have now: DNA verification, exposure to specific diseases and substances that can cause rapid natural deterioration of health, and lineage tracking to find targeted relatives.
Later: DNA-specific chemical weapons and targeted gene editing for compliant offspring.
Perfect the bioweapon against you if you aren't one who can be controlled.
Just from the tech we know they have now: DNA verification, exposure to specific diseases and substances that can cause rapid natural deterioration of health, and lineage tracking to find targeted relatives.
Later: DNA-specific chemical weapons and targeted gene editing for compliant offspring.
Avoid getting blood work from now and hope they didn't record anything permanently.