I would be cautious before accepting a claim like this, if only from the experience I've had with academics in the field. One of the most prominent 'specialists' on queer studies regarding Native Americans, Walter Lee Williams, has had a huge influence through his work but has since been thoroughly discredited as both a pedophile (look him up, currently in jail) and as someone who either misunderstood Native American culture or outright lied.
I met Walter Lee Williams once in Cuba, where he said a lot of similar things to what this article was saying.
I later looked his claims up and found a fellow scholar (who also happened to be gay) debunking it point by point, showing how Williams used anecdotes from lovers and misrepresented other sources in a way that seems to indicate a conscious effort to mold Native American mores into the perfect weapon to critique contemporary American culture in regards to the LGBT community.
Here is an article where specialists call him a liar:
Here is a thesis where an actual investigator debunks Williams point by point:
http://scholarworks.umt.edu/cgi/viewcontent.cgi?article=1810&context=etd
From what I've seen this part of the Queer Studies field is cleaning house and wiping away his 'too good to be true' narratives about an ideal Native American past (Noble Savage 2.0?), but some of his lies are still alive and kicking, so I'd be very wary.
Edit: /u/NorseWinter made some pretty good points as well!
It is a very diffucult question, and a question I would have a hard time answering wholly. I can however administer some solid source criticism. Looking at the wikipedia I see that the majority of source material is from one [Serena Nanda] (http://de.wikipedia.org/wiki/Serena_Nanda), atleast when making any postulates regarding what you ask about. A quick search reveals a long and productive career in gender studies, but most of her works are adressing hijras in India, which is in accordance with her [Ph.D] (http://anthropology.as.nyu.edu/object/anthroalumni.serenananda). She's an anthropologist and writer associated with John Jay College of Criminal Justice and retired. The cited work is Gender Diversity: Crosscultural Variations, accesible from [here I found worked for me] (https://books.google.dk/books?id=0XgbAAAAQBAJ&printsec=frontcover&dq=Gender+Diversity:+Crosscultura&hl=da&sa=X&ei=JLE2VdeDFMqLsgHViIHgAw&redir_esc=y#v=onepage&q=Gender%20Diversity%3A%20Crosscultura&f=false). I could find no reviews on any database I searched in including JSTOR, but it wasn't the most thorough search I do admit, so I might have overlooked something.
The first problem when I began reading this online book is; it is very sparsely cited. I found no citation to back that postulate that is used in the wikipedia article. That being said, it isn't wholly unlikely she's on to something, but that particular work is probably better to give an overview of the thematic field than as any sort of empirical source. The statement has however been present since the first iteration of the [Wikipedia article] (http://en.wikipedia.org/w/index.php?title=Gender_systems&oldid=400427970).
Edit: Done being a rulebreaker, sorry mods.