Eight members of a family

Question

There are 8 members in a family. Four of them have positive attitudes while the other four have negative attitudes.

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Among the group of four who have positive attitudes, the third member is the child of the first and second members while the fourth member is not.

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Among the group of four who have negative attitudes, the third member is the child of the first and second members while the fourth member is not.

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The third member in the group of positive attitudes motivates himself and receives motivation from other 7 members of the family too.

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The fourth member in the group of negative attitudes provides demotivation to other 7 members of the family and demotivates himself as well.

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Who are these people?

Answer 1

I think they are

Blood groups

namely

A, B, AB and O, with respective -/+ Rh factors

Resolved statements:

(1/2) AB has A & B antigens, while O has none
(3) AB+ receives from all and only gives to AB+
(4) O- gives to all, receives only from O-