With all the retcons, reboots and reimaginings that DC regularly subjects its characters to, quite a few have back stories that even its most devoted readers have trouble unravelling. Few, however, are as muddled or confused as those of Hawkgirl and Hawkman.
The irony here is that, although it can be argued some characters need to be retooled every decade or so simply to remain contemporary, the back story of the "Hawks" is one that should have ensured it would never have to be rewritten.
Essentially, the original characters - Carter Hall and Shiera Sanders - are the reincarnations of a ruler of Ancient Egypt, Prince Khufu, and his wife. They are destined to continually die and be reincarnated, continually rediscovering their love for each other only to die again. It should, therefore, have been perfectly possible to invent a new identity for each of them whenever it was felt the old ones were becoming dated. There should never have been any reason to rewrite any of the history that had gone before.
But DC, of course, is not exactly renowned for its ability to resist the urge to fix what ain't broke. The stories of Hawkman and Hawkgirl have been added to, subtracted from and otherwise rejigged to such an extent that the current "official" position as detailed in the DC Comics Super Hero Collection magazine (which accompanied Eaglemoss's excellent Hawkman figurine on this page) is virtually incomprehensible.
For my part, I must admit I find it it easier to just ignore the many confused and conflicting revisions of the past forty or fifty years. Despite the efforts of Geoff Johns and others to reposition Hawkman at the centre of the DCU (a position he hasn't held since he regularly chaired JSA meetings in the 1940s), my childhood memories of him are as a distinctly second-tier character. And, although I know she was his partner as far back as the Golden Age, I have no memory of ever having seen Hawkgirl at all before her wonderfully feisty incarnation as part of the Justice League animated TV series.
I have no idea whether, in the current continuity, they are supposed to be human or Thanagarian. I really don't care why, despite the fact that their wings are artificial devices (made, inevitably, from the now ubiquitous "nth metal") and held in place by a harness, the characters are seen without them even less often than Batman is seen without his cowl. The core story created for them by Gardner Fox back in 1939 is so strong that, as long as I keep that in the back of my mind, it enables me to ignore everything else and make some sense of even the most convoluted modern version of their lives.