Adoption: should everyone be able to adopt?

As a Minnesotan I often turn on WCCO radio when I am near a radio. One of my favorite programs to listen to is Jack Rice in the early afternoon. In actuality, I disagree with almost all his conclusions; however I enjoy thinking through the issues he addresses in order to better understand where I stand myself. This is how the following article came about. I was listening to Jack Rise discussing the subject and an argument came to mind.

Recently John McCain discussed a controversial subject, namely that of homosexual adoption. Should those couples of the same sex be allowed to adopt children? Many say that there are so many children in foster homes, it is unreasonable to refuse those who are willing to take a child into their home. McCain disagreed. Of course his campaign was quick to announce that he also felt this decision was for each state to make and that he would not impose his views on anyone. But think about it. Is it discrimination? Is it right? What is best for a child, to be just another kid in a foster home, or to be in a loving home with two moms or two dads?
With the rising numbers of foster children, it is important to find nurturing and encouraging homes. It would seem that refusing anyone who was willing to accept a child into their very family, providing for their every need, was foolish. Does the gender of the parents cause such a problem that a home should be refused to a small child? It seems that this may be an extreme does it not?
When this issue is discussed, people often describe those opposing homosexual adoption as intolerant and ridiculous. Announcing that, those people must just be afraid that homosexuals with children will only breed more homosexuals, they shun the opposition as ignorant. Yet, it does seem likely that this would happen. And from a purely practical viewpoint, if homosexuals adopt children, who themselves become homosexuals; the population of America will diminish rapidly.
Meanwhile the United States tends to be a leader in many ways. There is a loud voice calling for the preservation of natural resources and habitats. National parks, forest reserves, and the like are scattered across the nation dedicated to preserving natural wonders and homes for wildlife. It has become of the utmost importance to save for our animals their natural environment. For nothing can be expected to grow and thrive outside of its rightful home. Even when animals are taken to zoos great care is taken to recreate their homes, so that they can live naturally and well. Yes, this is still about homosexual adoption. Think about it. If natural environments are so vital to the healthy growth, life, and even happiness of animals, is it not the same for humans? The natural habitat, so to speak, of a child is in a home with a mother and a father. The very fact that homosexual couples cannot have children on their own makes them unfit to raise children. How can a child thrive in an unnatural environment?
In our attempt to sound politically correct, we are disregarding standards that are required for mere animals. Is this ethical?