Knowing RJ he probably has a real answer for this but here is my two cents.

The other day I was watching a show on PBS about williams'(sp?) disease. They said it occurs about 1 in 50,000 and what happens is the seventh chromosome is damaged. It was really interesting because those who have it look a lot alike and have certain characteristics. Highly developed social skills, music skills and Lingual ability but have serious spacial and numerical difficulities.

The point being, this is NOT a genetic defect. It is just an imperfection. But if someone who has williams' disease were to have children there would be a 50/50 chance of passing it because it is now a genetic defect. Back to the theory:

The enormity of genetic diversity could allow for random occurances that in the child would allow for the ability to touch the true source. This being their genetic code would then, depending if their mate can channel, pass it 50% or 100% of the time.

The next question is how is strength determined? obviously the channeling gene would be a combination of genetic patterns when added up gives the whole person. overall I think RJ would be smart not to touch on this subject at all. It would allow for to many issues to arise. Genetic manipulation for stronger Talents or plain ability. Cloning. sounds like a can of worms to be left alone.