Kimberly is correct that there are several relevant, analogy-breaking differences between (for example) a homosexual male non-pedophile adopting a young male child, and a heterosexual male pedophile adopting a female child.
1. The homosexual male non-pedophile is not attracted to young male children; he is attracted to men. So sexual attraction to his charge is not an issue in that case. And sexual attraction to the adopting parent's charge is one of key problems under discussion.
2. With respect to the "pedophile vs gay" comparison in general - an adult man is considered responsible for his own actions; he can legally consent to sex. It is not automatically considered a form of rape. A child is not considered responsible for his or her own actions; (s)he cannot legally consent to sex. It is automatically considered a form of rape. Whether you think this is morally right or not is another topic entirely. At issue are adoption considerations. So long as the above is true, an analogy between gay adoption and pedophile adoption is further broken.