Apologies for the lack of hard evidence, but I can't remember which book it is. However, in one book it mentions in passing of a Tuatha'an Aes Sedai. So I'm positive that females among the Tuatha'an that turn out to be wilders head to the White Tower. As to the males, I agree with GrandpaG, they are exiled. Remember in the fourth book when Rand goes to Rhuidean and has all those memories? In one of them, one of the Tuatha'an throws himself off of a cliff when he learns he can channel pg 421/422.