Dr. Pete Peterson also talks of this in an interview conducted by Kerry and Bill / Camelot. But I don't think he nailed down any specific blood type as I think that is an assumption that got started like a rumor because of the 15% factor just so happen to match up with the 15% of what could be alien DNA. It would be interesting to see if this factor proves out to be the same RH blood type but my gut says it is not. That would be a good question that could be asked for the Doctor for the next interview. Just a thought. It is a really a very informative piece. Part one gets into it.
http://www.projectcamelot.org/pete_peterson.htm