At a deep level, everything is duality and paradox. There are the dualities within oneself, the good and the bad, the wise person and the fool, the strong and the weak, the ugly and the beautiful. We are, each of us, all of these things.
Yin and yang is an ancient Chinese representation of these dualities. Part of the dualities represented by the yin and the yang are male and female and light and darkness. At the deepest level the dualities resolve into unity. Everything is one. This is why the yin and the yang are not separate but intertwined in the symbol.
I, myself, am two-spirit. I have both the strong, powerful male spirit, and the nurturing, compassionate female spirit within me. Yin and yang are intertwined within me. Two spirit is a modern word coined to represent the fact that many native American societies traditionally recognized individuals who did not fit neatly into the male-female gender dichotomy. The First Nations people of the Americas were ahead of Europeans in many ways. The recognition of the importance of women being equals and the need for women to have a say in decision making, of humanity's role as stewards of the environment, a greater spiritual awareness, and respect for individuals who were not clearly either male or female are a few of the ways that First Nations peoples were centuries ahead of the Europeans who first arrived on this continent. It is a pity the first Europeans were so arrogant and attempted to destroy the cultures of the First Nations. If they hadn't been both groups of cultures could have developed more quickly from learning from each other.
It is true that my current physical body happens to be that of an anatomically male human and that my current biological brain happens to be wired in such a way that I experience sexual attraction to other anatomically male humans. I am not my body, however. I am a soul who is entwined on a deep level with my physical body, but I am not my physical body.
I find it odd that many on the political and religious right get so worked up over the number of penises that couples have between them. Really, has God gotten so bored that he has resorted to doing penis counts? The wars, pestilence, disease, famine, environmental degradation, rapes, murders, torture, fear, pain, terror, and suffering that are prevalent on this planet are apparently, according to certain members of the religious right, not enough to occupy the thoughts of this omnipotent, omniscient, perfect in morality being so he instead resorts to doing conducts penis counts in loving couples and gets pretty cranky when the appropriate number of penises aren't present. Does this make any sense to anyone? I know people says that the Lord works in mysterious ways. This isn't mysterious, however, this is downright nuts.
I have identified as gay most of my life. I recognized my sexual attraction to other males at the age of 10. I feel that a term that describes whether or not my partner has an innie or an outie, however, is of such trivial importance that it is not even worth mentioning. Even though I am not a native of the Americas, and I am not transgendered, I feel drawn to the term two-spirit. It seems to represent a deeper, spiritual aspect of my personality. Spiritually speaking I am androgenous, neither male nor female, but I instead have aspects of both.