Well, I've finally finished Lupa's "A Field Guide to Otherkin," and I must say that I am quite impressed. It is written from the perspective of an otherkin, but she has taken great pains to treat the subject impartially. There is a meaty Bibliography that those who wish further reading will find very useful.
Topics covered in the book include such things as theories of being 'Kin, including personal psychology, metaphysics, personal mythology, energetic resonance, and the genetic thoughts. Therianthropy, Vampirism, and several other types of 'Kin are mentioned in the book, and some types of 'Kin have whole sections devoted to them, with information drawn from collected surveys.
As to the surveys, having tried to gather research on a different topic before with this method for college, I can understand how hard it is to get a good sampling of any community. One hundred thirty one, including her own response, is far more than I ever got for my alienation report. I was very surprised by the breakdown of the 'Kin types that responded, for example I thought that there would have been far more kitsune than the single response from that type received, although the greater number of wolves I did expect. Perhaps some day she will have enough information and additional responses to put out a second edition.
Magic and Spirituality is also touched on this this book, and in quite a responsible and adult manner to my finding. Thoughts on how to become 'Kin to the Other as well as the possibility on how to stop being 'Kin are presented, and the same goes the the opinion of one unbiased psychologist.
One of the things that I liked best about this book is that the author highly stressed self-exploration, common sense, and a large dose of salt.
Whether one is 'Kin themselves, suspects that they may be, knows someone that is 'Kin, or just interested in the phenomenon and/or experience of being 'Kin, this book I would consider a must read.