what is there a chess gene? 

or maybe this whole topic just a way to discuss, again, the relationship between i.q. and chess without stating it upfront? 

seems pretty clear to me that anyone who is highly intelligent will be able to attain expert strength at least. to get to FM, IM, GM level you probably have to be an SD or two above the average in regards to intelligence, but intelligence is not the only factor. it's only one part of the equation. it's readily possible to have two people with nearly identicle i.q.'s but one of them being a much better chess player. 

Of course there is not a 'chess gene', but it is likely that a large part of your chess potential is genetically based, depending on the scope and type of your intelligence.  As you say, IQ is not the sole factor in determining chess potential, certain people are more naturally inclined to the type of thought processes that high level chess requires.  So you've already admitted that a reasonably high level of intelligence (a largely genetic factor) is a prerequisite for being a strong chess player, I would say that the other factors are genetic too.  Even work ethic, which is necessary to reach your potential, is probably genetically influenced.

The idea that the love of chess is engrained in your DNA is unscientific.

Chess is an abstract concept. Likes and dislikes cannot be passed from one person to another.

If a man loses his arm in his thirties, that does not mean that his son will be born armless.

The same applies here. 

I suggest you study up a bit more.

"While all cells in your body contain essentially the same genome, the chemical tags on the DNA and histones get rearranged in different cell types. The epigenome can also change throughout a person's lifetime.

Consider the case of identical twins. Although they share nearly the same genome, their bodies may not be exactly identical. One twin may weigh more, for example, or develop arthritis. Researchers think that at least some of these differences are due to changes in the epigenome."

http://www.genome.gov/27532724

Video:

http://www.youtube.com/watch?v=s7dDd1bvNfA

None of it! None of it is talent or how hard you try or study or any of that nonsense. It's all luck. Just plain ol' simple luck, like flipping a coin. Chesss is just all luck people