Adeptogender is when ones gender identity was discovered or helped to be discovered by the realization of ones kinself. One's gender identity does not necessarily have to be related or tied to ones kinself (kingender) to be adeptogender. For example, one may realize they are transgender after going through the process of finding out they are otherkin, and would not have realized they are trans if they had not gone through and finished the process.
The term adeptogender seems to have been first coined on a site that mocks non-binary people, however this site was taken down. The terms coined there were reposted by the Transgender Teen Survival Guide on December 26, 2016, and have been used in a better light since. It is unknown if the person who posted these terms was aware whether or not the site they posted them on was offensive.
The flag was coined on October 29th, 2018 by user Anya111. The brown stands for kintypes, pale stands for the realization, and green stands for any gender.