I have suspected since about book Six that the (by now) ex-president of the Unites States, Leo Barnett, is a son of Dr. Tachyon, and a Takhisian/Human hybrid.
Originally I though Blythe (Brain Trust) gave birth to him in the asyleum, but he would not have been able to pass the blood test if his mother was an Ace.
The reasons I believe this: Golden Boy was utterly certain he was using a mind control power on him. Now, Jack isn't a very bright boy. But he does know mind control. Possibly better than any other human being. He lived with the Envoy, whose power could not be turned off.
He hung out with Tachyon who disrespected him enough to casuallly mindcontrol him when irritated. And Blaise. He knows mental control. And he was rock-certain Barnett used it on him.
Second, the vain Tachyon with the enormous ego thought him handsome.
Third, he avoided Puppetmans power like a pro.
Fourth, he does not seem to age like a human, although it is early to tell. At sixty, he is described as wrinkle-free and young looking to a degree that amazes even Billy Ray. As Tachyon said to Blaise "You will live longer than a human being."
Fifth, he is not an Ace, the blood test was pretty certain.
Sixth, his attitudes are distictly Takisian, once you strip out the religous stuff.
Seventh, the authors use "mentalist" to describe Takisians, as opposed to the "psychics" of the wild card virus.
The character list describes him as, not a "fundamentalist", but a "(funda)mentalist".