A non-religious evolutionary argument against homosexuality

According to Darwin's theory of evolution the male and female were brought into being in order to perpetuate the species.  The organisms with the strongest traits are the ones to find mates and procreate allowing only the strongest organisms to pass on their genetic material.

How does this relate to the human animal?  Human females were created with an inbred need to procreate, rear and nurture young while the male of the species were created with an inbred need to procreate, protect and provide for the mate and the offspring allowing for the best environment to raise offspring to adulthood.  Those who do not have that innate instinct do not procreate and do not pass on that trait limiting the amount of new births of humans with that trait.

 The purpose of the female and the male is best served when a permanent bond between the parent organisms is created.  This permanent bond allows for each parent organism to do their part in ensuring their offspring have the best possible environment into which they will be able to survive to adulthood.

Those with predispositions to same sex attraction do not align with this purpose of perpetuating the species.  Those with these predispositions claim that they were born this way and that there is nothing wrong with that.  Since this is in direct opposition to the purpose of perpetuating the species and there is evidence that there is some kind of brain or chemical imbalance causing this phenomenon the theory of evolution will argue against that.  In any other brain or chemical imbalance you will find treatment with medication and or therapy.  Unfortunately those with this particular imbalance refuse to even acknowledge that their instincts are a genetic anomaly which by definition is abnormal.  Many schizophrenics also believe that and are institutionalized for their own safety.

Here is where the theory of evolution proves itself.  Those with the inclination to same sex attraction make physical alliances with those of the same sex they are attracted to hindering their ability to procreate and once again limiting the instance of this undesirable genetic trait.  Since there are no offspring to raise and protect from these alliances then there is no need to create a permanent bond evolutionarily speaking of course.