The people who use terms like ‘royalkin’ or ‘princesskin’, or for sake of example, lawyerkin, janitorkin, stockanalystkin, zookeeperkin, blacksmithkin, etc etc…. fundamentally misunderstand what the term ‘kin’ denotes.
Being royalty is a position you hold during life, it is a role, not an identity, even if you’re born into it. It is not a unique state of existence the way a bear is, or a unicorn is, or Ash Ketchum is.
Spiritually speaking, if you are reincarnated from, or have an ongoing spiritual identity connection, with Phoenix Wright or Atticus Finch does not make you ‘lawyerkin’. Both of them act as lawyers but its something they DO not something they ARE. There is no fundamental difference between them and any other human being. The same would be true if you were spiritually kin of a bird who was a lawyer. You’d be birdkin, not lawyerkin.
Psychologically speaking, there’s not way you can be ‘psychologically’ royaltykin (or lawyerkin) either. Any difference in mindset between a princess or lawyer and any other person, (or bird) is a matter of training, not a matter of fundamental internal difference. (If you think you are psychologically a princess and that makes you fundamentally different from the rest of the human race I have a bit of likely unfortunate news for you about your personality.)
You can not have a kintype that is the result of training or upbringing. You can’t be mailmankin. If you believe you were John Q. Mailman in a past life, that makes you reincarnated, and possibly kin if John Q Mailman was a bird, a unicorn, or a fictional character. If you believe you are psychologically a mailman, and have a compulsion to deliver letters, all that makes you is probably very suited for a profession as a mailman.
There is ONE exception I can think of for “royalkin” ONLY, (not mailmankin or lawyerkin) and that is specifically if the royal family you are a part of is descended from the gods, or is considered to be divine. And that makes you divinekin, not royalkin.