In Humans, Rhesus condition can arise when,

1. father is Rh+ and mother is Rh-
2. father is Rh- and mother is Rh+
3. either father or mother is Rh+
4. either father or mother is Rh-

Hi Gaurav,

In Humans, Rhesus condition arises only when the father is Rh⁺ while the mother is Rh^- and the baby is also Rh⁺. When such a condition arises, then antibodies are produced in the mother against the fetal RBCs and results in a condition known as Erythroblastosis foetalis.

If both the father and mother are Rh⁺ or if both are Rh^- then the condition does not arise.

Hope you find this answer helpful,

Cheers!