I get this question a lot and hear the claim even more, but must add I can think of 2 or 3 individuals who I wouldn’t qualify as intelligent being the loudest in terms of making this claim again and again.
Your intelligence cannot be measured by a number. It is defined by your willingness to learn, solve problems and try new things. You are more than just a number. Develop your skills. Share your brilliant ideas. Your skills are more valuable than your grades.
Source: Prof. Feynman
So here is my answer:
There is only one study I have seen thus far.
And since you are Rh negative and intelligent, it shouldn’t be an issue for you to draw a few conclusions and explain to me what you read: