I am Y DNA haplogroup I1 (S19986) and my maternal haplogroup is T1a1 (full mitochondrial sequence on FTDNA).
I'm not exactly sure what my blood type is: I'm definitely O but I'm not sure about my Rhesus status, to which I will soon explain.
In my 7th grade science class we once had a class project of learning our blood types with EldonCards: I wasn't sure what to make of my results so I took them up to the teacher, and he exclaimed, "You're O negative, the universal donor!"
In the late summer of 2010 I tested with 23andMe; I also decided to retest my blood type with another EldonCard: the results were clear to me that I was still O negative.
Then my 23andMe results came in and the "experimental" blood type test feature said that I was O postive (+/-).
A few years later both my parents tested with 23andMe and their "experimental" blood type predictions were: O negative (-/-) for my father (maternal haplogroup V) and O positive (-/+) for my mother.
My brother is O negative as far as I understand: he once donated blood in his teenage years with a girlfriend and became very popular with the Red Cross for a while.
When I had to reconcile my EldonCard results with my predicted DNA results was when I first heard of Weak D blood types. I'm still wondering just what exactly my Rhesus status is.