Of course we can. Marriage was invented so that children would be raised within the natural family environment. Its not rocket science. Only people who do not hold the natural family as important would come out with something so ridiculous.
Well we have a difference of opinion. I think the make up is important you obviously don't see the importance of the natural family. Which is quite common with people of your ideology.
Why is the makeup important? If a child grows up with two loving parents, why does it matter if they are of opposite or same genders?