Baker boy. If that statement held any kind of truth there would be no gay people. All children are born from a male/female union, and brought up in a male/female environment, for the most part. Most gay people have been brought up in a heterosexual environment, it didn't 'prevent' them from being gay. Being gay is not a lifestyle choice, it is who they are. And they should be allowed to live their lives with the same rights as everyone else, without fear of prejudice or persecution.
In adoption the child's needs should always be what is important and if that means being adopted by a same sex couple, I don't see a problem.