hm, I can't really help here, because I didn't get my head around this fully, but I tend to think Brennan is referring to the different phenotypes that result from using different metals as so to say control units in the cells combined with Blood types. When iron is used in rhesus negative types, u get more like blue eyed and blond haired people, with copper instead in rhesus negative types combined with other blood types u get more green eyed and red haired people. I only read about this once and cant remember when and where. (so that is where there is no help from my side)
I myself am, according to my own baby pass, AB neg. . I do not know whether this is correct or not. I cannot find anything blood type related about my pregnancy 18 years ago, and back then I do not remember anything done to me (like a passive vaccination, and I would remember that!) or anyone saying anything about possible complications with the pregnancy. My son is B pos. . Eight years ago I had a miscarriage, quite early in the pregnancy, about week six or seven. That said, I am green eyed, red haired, high cheek bones, slim... everything you would translate with "celtic".
So maybe it is true, that I am rhesus negative, although nobody in my pregnancy told me about that ( and I didnt know, to admit that). I could simply do another blood test, but somehow I do not at all want to...