u/Zap_Powerz : first of all "Nephilim" were probably evil ones,or experiment targeted by some aliens to be wiped out.

Second of all: too much genetic mixing to treat blood group as important genetic factor. It is currently not after so much genetic mixing, despite the fact it could be mutation caused artificially with some purpose

Third of all: Why are you asking about those people. According to those article:

http://themillenniumreport.com/2017/02/why-are-tptb-tracking-people-with-rh-negative-blood-so-closely/

It claims such people are "monitored" and even hunted. For example:

The vast majority of them are completely unknown to themselves as well as to their communities. Only the government really knows who they are given the efficacy of the NSA spying and surveillance network, which effectively owns and operates the World Wide Web. Only those who are not telephonically or digitally connected are relatively free from such microscopic scrutiny of their lives and communications.