Genetics do play a surprisingly significant role, and my second reference (book) even mentions it in the title. IQ is strongly believed to be linked to genetics, but again, as I listed in one of the sources, even IQ doesn't necessarily factor into skill acquisition, only
ease of skill acquisition; two distinct but important points. You can learn to learn better --
that is the main point. It doesn't matter where you start off (i.e. IQ via genetics), you can still get a skill snowball-effect going relative to where you started. It seems you missed the second part of my last comment where I mentioned it was more segmented and context based (like your citation states), but that the
general trajectory is still the same. Learn a skill in one context, any subsequent skills in the same context become easier. The thing is that there are things that generalize to multiple contexts, and that some contexts are larger than they seem[1].
Now, it is certainly much harder for some people to acquire certain skills, and it may be near impossible to excel at them up to a certain level (e.g. physical athleticism). But skill level is again different from the skill itself, and it is the skills themselves that matter in skill acquisition. For example, if running ability is found to be genetically limited, then getting any better at it may be harder for you, but picking up a sport like football would probably still be much easier for you if you trained your running first regardless. IQ being genetically determined can impact other things like motivation; i.e. if you have a low IQ things will be harder for you, making you less likely to pursue skill acquisition in the future, and conversely, a high IQ may predispose you to acquiring more skills since they come so easily to you, but the point is that neither absolutely determine how many skills you can/will acquire.
I made a 'bold' statement because it's just that practical of a perspective to take[2]. And science backs it up not only in terms of all the positive effects exercising brain plasticity brings[3], but also in the fact that IQ isn't an end-all be-all metric. It is significant, and highly correlated to other important things like life expectancy[4], but IQ itself is not the limit. A built-in limit to skill acquisition would have to come somewhere else down the line if there is one. I study this stuff on my free time because it interests me, I'm not an expert/scientist, so trying to discover a well-defined concrete limit to skill acquisition is beyond my domain, but stuff like epigenetics and plasticity is making it harder to believe there is one.
[1] I believe the last cite in my previous comment shows an example of this. Also, I myself have a pretty average IQ of ~114 or something, but this view has allowed me to learn a surprising number of skills before I even knew any of the science around it, so of course I'm biased and wanted to share.
[2] Well, that and the fact that most people simply don't bother to look at painfully constructed source lists anyway, making the endeavor of compiling them less worth it.
[3] One example: http://news.stanford.edu/news/2003/september24/dementia.html
[4] http://www.mrc.ac.uk/About/AnnualReview09-10/SevenAges/Elder...