Yeah, we have evidence of it in DNA-DOA, which is about a sold as it gets.

Also in Shadowtech, and in a few other areas. (KAM is usually there to go, "Uhm. Boy. It';s ... hard. It's really ... really hard.")
In essence, the magic gene has a 5th dimension that you have to be watching astrally to catch, and even then, you kinda have to be watching right as it expresses, since magical talent starts awakening aorund puberty. CLoning babies doesn't pan out for several years, unless you speed-grow 'em, and none of those have pinged positive ... which means that the process itself might leech any magic out of the subject, or they just haven't cloned them right, or they didn't watch the right place at the right time, and, hey, if you give us a few more million in funding, we're SURE to get it next time, right?
Absolutely the Holy Grail of genetech, but nobody's gotten even close, yet.