So, this is something I don't recall ever being mentioned: What mutations have occured among the Arroyo people?

In recent play through of FO2, Richardson makes mention of interesting mutations that occured, that under other circumstances they would want to study, but alas, gotta go through with Enclave super plan
Now, seeing how Enclave would only be interested in something that was actually beneficial, what could it be?

I would think it was: increased resistances to environment/ toxins/radiation.

Psionics.

Any other ideas? Maybe increased healing rates?

Clearly whatever it is, the "mutation" is not visible and was discovered via Enclave testing.