The favorite justification for nearly any progressive initiative is that "it's for the children."  Surprisingly, though, when it comes to the culture war over homosexual marriage, you'll never hear children mentioned in the various arguments advanced by proponents.

Yet homosexual (or gay) marriage truly is all about children, and we'll see why shortly.

But first, no matter how you feel about religion in general or conservative Christians in particular, I think most civilized people would agree with the following excerpt from the recently publicized Manhattan Declaration by a coalition of Catholic and Protestant clergymen:

Vast human experience confirms that marriage is the original and most important institution for sustaining the health, education, and welfare of all persons in a society.

No doubt many gay Americans would agree.  Which is why, perhaps, they would say they are entitled to the same recognition and governmentally conferred benefits as married heterosexuals.  Indeed, they say that it is a question of civil rights.  And if you don't agree, you're just a homophobe.

But what's really at the heart of the homosexual civil rights argument with respect to the specific question of government-sanctioned gay marriage?  The answer has been completely shrouded by the misdirection outlined above, and it has nothing to do with hatred or bigotry.  Rather, it has everything to do with science and, ironically, children.

While many progressive gays -- and the left in general -- happily use science, especially Darwinian evolution, to denigrate God and religion, they ignore the many correlate scientific implications of evolution's fundamental mechanism: natural selection.  For those with even a cursory knowledge of the science, the obvious truth is that homosexuality has, in evolutionary terms, a negative survival value for the species -- since homosexuals are less likely to reproduce -- and is by definition a dysfunction.

Naturally occurring?  Yes, certainly.  Normal?  No.

Make no mistake: this is not some highly speculative theoretical construct, such as modern physics' String Theory; it doesn't require quantum-mechanical mathematics.  It is more on the order of an axiom, which is to say that it is self-evident.

Unfortunately, the "political correctness" cudgel more or less guarantees that most working scientists whose specialty is evolutionary biology would be hard-pressed to admit this -- because virtually all American scientists are the product of U.S. colleges and universities, where huge majorities of the faculty are self-described liberals for whom political correctness is an article of faith.  These scientists, many of whom still work at those colleges and universities, would never allow themselves to put at risk their job, their grants, and their prospects for tenure.

Perhaps most importantly, the recognition of the nature of homosexuality clearly and definitively refutes former Solicitor General Ted Olson's main argument in the California Prop 8 case, horribly and misguidedly decided by Judge Vaughn Walker, that gay marriage is a declared right because of the Supreme Court's decision in Loving v. Virginia, which struck down the ban on interracial marriage.  However, Olson, perhaps unintentionally, is making a wild conflation between race and affective impulse with evolutionary consequences.  In other words, race is not a dysfunction, and gays come in every racial variety anyway.

Does this mean that gays are evil people?  Not at all.  And yes, they deserve every right that everyone else enjoys, as long as we're talking rights, not wishes.

So is it a right to do something for which you are unqualified by virtue of an inherited (genetically and/or congenitally caused) disability?  No, and I will offer my own experience by example.

From the time I was five years old, I dreamed of being a fighter pilot.  As an undergraduate at the University of Maryland, I took the first step by enrolling in Air Force ROTC, but I soon became unqualified for flight training because of a decrease in my visual acuity due to newly diagnosed myopia.  Was it my "right" to demand that the government spend what was at the time more than a million dollars on my flight training just because I wanted it, even though I didn't meet the government's standards?  Absolutely not.  Rightly, the government decided that our collective scarce resources -- in the form of tax money -- were better used on candidates who, though not otherwise better-qualified than I, met all the standards and were devoid of any undesirable traits.  Now, I did go on to become a commercial pilot and flight instructor, but I did it on my own dime.

Similarly, gays claim that the government should allow them the same monetary benefits, mostly through tax preference and legal recognition for things such as inheritance rights or end-of-life visitation privileges, as heterosexuals.

Why, then, is it okay for the government to continue to grant preferential treatment to heterosexuals when it comes to marriage?  To most of us, the answer is obvious.  There is only one reason government has any interest in marriage: heterosexuals bear children.  They create and socialize the next generation of citizens.  The best environment for the successful development and socialization of children is a marriage between a man and a woman (and those who clamor for gay adoption should take a moment to think of the implications).  Most well-designed studies prove this.  The government, as the promoter-in-chief of community welfare, is right to offer incentives for this outcome through support of the institution of marriage.

After all, if gays want to have a marriage ceremony, they can.  If they want legal rights via personally obtained civil unions that confer privileges similar to those of government sanctioned marriage, they can have them.  But with our country facing daunting fiscal problems for the foreseeable future, can we as a nation afford the luxury of providing a class of people with a certain disability a costly benefit that is the equivalent of a bad investment?  I don't think so.

Broadly educated in the physical, social, and biological sciences, Carlton Austin is author of Second Eden and publisher of online aviation and space magazine Aerosphere.com.