Bad genes and genetic mutations;

In genetics there are mutations that are recessive, whether or not they assist or detract from survival. One of the arguments that obfuscated the Darwinian status of Hitler's Super-Race was the observation that both Blue Eyes AND Blond Hair are recessive genetic traits. In fact, I have heard that statistically, Red Hair may "go under" soon. In that context, I would like to talk about two separate tendencies that have been demonstrated as having genetic components. I'll ask if they might be recessive or dominant, and in either case how they have influenced Evolution. A dominant gene of a dis-advantageous trait should impede proliferation, under the theory of natural selection, while a recessive gene of an advantageous trait might fail by evolutionary accident. The two behaviors I have under consideration are alcoholism and homosexuality. Alcoholism is a genetic trait that is dis-advantageous, and is not thought to have influenced evolution because alcohol itself has only recently become available. The genetic component is such, that IF you have the trait, you develop alcoholism with undue ease in person and undue frequency in populations. Despite the fact that a genetic pre-disposition changes ODDS, lacking the gene is no guarantee of exception to the rule: almost anyone can, "by dint of much effort," adapt his system to require alcohol for metabolism. After that, enforcing choice by intellect on the decision is to overcome a constant chronic injury. Under these conditions, I think it is worthwhile to ask if alcoholism is a dominant or recessive gene. I have left genetic homosexuality to be last, not least, for context. Does the genetic predisposition eventuate the practice? Are all practitioners subject to the gene? Is it a dominant or recessive trait? On the off chance it is BOTH recessive and dis-advantageous (superficially by inhibiting reproduction,) how has it survived Evolutionarily? Is it possible, as Christians seem to demand, that any individual can exercise choice over it, despite genetic predisposition or other acquisition of the trait?