Marriage is a very controversial point of dispute between opposing groups supporting and opposing gay rights. Many individuals have absolutely no problem granting basic human rights to lesbians, gays, bisexuals and transsexuals provided they stay within their limits. To enjoy medical assistance, fundamental rights and property rights in society is one thing. To demand the right to marry and adopt kids is, for many, a completely different thing.
Well, it is not possible to offer human rights in a structured or staggered manner. If homosexuals are considered as humans, they should be afforded with all rights that humans have. In any case, the United Nations charter clearly speaks that access to human rights is not a matter of choice offered by majority in government or society. Rather, it is an invaluable right of each and every individual. All civilized nations, America included, function upon this touchstone.
Marriages are controversial point because the idea of sex between two persons of the same gender is considered unnatural. The fact that nature allows procreation only between members of the opposite sex is offered as proof that homosexual is unnatural. Well, fact that human beings fly across continents in planes is equally unnatural. Had human beings meant to fly, nature would have granted us wings. However, this has never stopped people from making use of this convenient form of travel.
The whole argument of natural and unnatural relations is a farce. It leaves too much freedom in the hands of those who presume authority to speak on the subject. To consider marriage as a religious or moral bond leads to complications. If it is viewed as a social contract, there is absolutely no problem in persons of the same sex marrying each other.