A recent study states:
The study found that the blood group (AB) received the highest average in the Intelligence Quotient (IQ) test which is also the highest in the GPA. And that the blood type (B) was the lowest in the GPA and in test results. The researcher recommended to expand the circle of the research to include all Jordanian universities , other universities and schools in a longer periods of time.
https://www.academicresearchjournals.org/IJARER/PDF%202014/September/Atoom.pdf
This is not our own study. It is also done with a relatively small sample size.
Rh factor was not included in the study. It is however the main factor here: