One headcanon I have about synths is that they’re entirely organic except for two things: the plastic chip in their head, and their TEETH, which are made out of ceramic, and every single set is cast from the same mould.

Normal human teeth are already weird enough, so when you’re actively fucking with genetics I imagine things very easily go haywire with their jaws and mouths and it causes a lot of pain/is “unsightly” so the Institute just decided fuck it and instead of messing around with whatever needs-braces gene they gave the synths, it’s easier to just remove the organic teeth and implant new ones. But there’s no reason to make more than one mould, so every single gen 3 synth has the exact same set.

So theoretically somebody could identify every single synth out there with a 100% success rate, but 1) wasteland dentistry is in the GUTTER, and 2) who the hell would compare teeth?? Even if somebody did a full body examination and learned the teeth are ceramic, there would be no reason to compare to those of another synth.