There is a possibility that one or more otherkin is simply deluded about what they think or feel, and they are not kin at all. It is healthy to at least humor the possibility one way or another that kin may be delusional, or they may be right. There is a great deal of suspension of disbelief in the otherkin community, and many otherkin give at least passing acknowledgement to the fact that they might be deluded.
The typical diagnosis for such a person is schizophrenia, but there are other conditions that can create this sort-of situation. This is not true for everyone, as the nature of one's 'otherkin-ness' is different from person to person. Not to compare otherkin to mental illnesses, but it is an unfortunate possibility which many people, who do not understand, lump all Otherkin-related people into.
It would benefit both groups to try and remove the stigma associated with mental illness by trying to educate those that do not understand the concept of Otherkin and mental conditions.
I myself went through an experience that was quite possibly my awakening. If it was, I was not ready, and either way I went through treament for my delusions and have since recovered and not relapsed. An experience I would not wish on anyone. Unfortuneately some of the symptoms (including paranoia) are both signs of awakening and the onset of mental illness (how much they are related is unknown presently) so I will most likely net really 'awaken' for a long time. It worked out for the better though, for when I was still mostly normal, I was taking theory and vague feelings too seriously and the whole experience has dosed me with a dose of healthy skepticism. Don't test the depth of the water with both feet.
Also, just bcause one is disagnosed does not take-out the possibility that one may still be otherkin of some type. But it is a dangerous topic during and shortly after recovery (I stepped out of the otherkin community for serveral months until I felt it was safe for myself on top of my psychiratrist's advice to do so). One must always question if what they feel is for true. You never know. I do not believe that all otherkin are delusional but some people do. And even if it is not true, the average person would think so. Believing that one has a 'real' imaginary tail at the age of 35 is far from normal compared to most people (though we are not most people). I am living proof that they are right, sometimes. But learn from my example and don't follow your feelings blindly. Listen, think and question.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." -Mark Twain.
-Peaceofmind
Author's Note: Mental illnesses, especially schizoprhenia, is no laughing matter and should be treated with all seriousness. Do not use this article as the means to diagnose someone of such an illness or something like it. If you believe that you or someone you know is suffering untreated, consult a physician and do not attempt to treat them yourself or recomend that a treated person to stop taking their medication. There are proven instances of people who spent years working on themselves until they could stop their medication and stopped taking them with their doctor's consent(without any conection to otherkin, it's community or the supernatural in general). But such a thing takes years and should not be replaced with short-term solutions. Not to disbelieve in the power of faith or possible spells or rituals, but they are unfortuneately not completely proven or reliable all the time. Neither is medication for that matter, but it makes the situation liveable until the person can treat themselves(as above) or until medicine becomes advanced enough to cure such ailments. And above all, leave the diagnosis for a trained and licensed doctor. Thank you.