I wish I knew as I'd make a fortune! 😂
Based purely on a radio show 30 years ago when someone was referring to "doping" in the States and said it was not to do with bloods, steroids or testosterone (which were the go-to at the time). I can't truly remember the specifics but vaguely DNA or genes.
Like others, I'm not in denial but I'm struggling to spot plausible performance enhancers that will produce a Pog from the peleton. Saying genes or DNA doesn't get us any closer to what is being boosted. If we could get genes or DNA into the body with anything better than miniscule efficiency then cystic fibrosis, muscular Duchenne muscular dystrophy, many cancers, and many other genetic disease would be cured long ago. Advances have been made but we're still a long way off efficient delivery.
In competition, we're still left with oxygen uptake as the limiting step in (aerobic) performance. This would likely mean an elevated haematocrit so risk biopassport violations. Testrosterone boosting (maybe by increasing expression of the testosterone synthesising enzymes) would be much more useful out of competition to boost muscle, and will take a good while to kick in. And I'm not sure how much benefit muscle building would benefit climbers (as opposed to roulers or sprinters).
Illicit methods to boost recovery is possibly an area for exploration - what I suspect the Sky Fluimucil decongestant (N-acetyl cysteine) story was really about.