Near the end of the third season of Black Lightning, Lynn hypothesizes that all the stable metahumans descend from a subject zero,
This would explain why the Pierces are stable, but none of the other metas of the same origin are. Obviously, excluding Lazarus Prime, Khalil, Tobias, and others whose powers derive from other sources.
So far, so good, right? We see that from the original batch, metas like Technocrat (TC) are unstable, and suffer health problems that worsen if they use their powers. Anissa, Jefferson and Jennifer are the only stable metahumans.
Except, are they? The teleporting meta who works for Markovia seems to be pretty stable. The same goes for the power copier in the service of the ASA. Ditto for Cutter from the last season, who has low-grade telekinesis. They are all adults, and don't appear to be exhibiting the instability that required the other metahumans to be put in stasis. Most notably, the meta leader of the Sangé in the second season was from the same generation of experimentation as Jefferson, but seemed perfectly stable (at least in terms of physical health).
So why are all these metahumans stable, if the "Gravedigger gene" is the determinant factor?