Do genes have any effect on whether a person will believe or not? Does this case eliminate man's responsibility?
Being intelligent or not is not proportionate to having belief or not. If it were like that, it would be unjust. Then, those who were very intelligent would believe and those who were not so intelligent would not.
Having belief or not is directly connected with man's will. People who are sane, whether they are very intelligent or not so intelligent, are held responsible. Responsibility is related with being sane or not. It is up to man's will to believe or not. Man accepts or rejects belief with his will.
Satan rebelled though he was very intelligent and he knew Allah. Rebellion does not originate from the insanity of Satan. The factors that you mention can affect whether man will believe or not but the real factor is man's will. None of these factors affect man's responsibility. Those who are not sane and those who have not been informed about Islam are not held responsible.
Genetic structure does not affect man's will one hundred per cent. It can only be one of the causes. As a necessity of testing, there will definitely be some causes that affect man's belief. However, none of them affects him one hundred per cent. If genetic structure were effective one hundred per cent, everybody would have to believe like Hz. Adam. After all, the genetic structure of all people comes from Hz. Adam. Hz. Noah's son was destroyed during the deluge before he believed in his father, which shows that genetic structure has no effect on the issue of belief. Man has the tendency of both believing or unbelieving in his nature. However, they are at an equal level.
According to the tafsir of Sa'd Taftazani, belief is "a luminous light granted by the Eternal Sun (God Almighty) and a gleam from the endless bliss." (Said Nursi, İşârâtü'l-İ'câz)