Biology of hermaphrodite species

How from a evolutionary standpoint hermaphrodite species can exist and have a good genetic diversity, with no self-impregnation?

But, this race visually looks more like females, they do have breasts

I think of two options:

Two individuals always impregnate each other, there is no "male" or "female" roles. But they have reproductive system, based on male and female biology, with no chance to an individual impregnate themself (how to justify that?)

Or there is a completely different sex, not based on human like reproductive sistem, no male or/and female organs. But how would that system looked like and worked, what biological justifications can be for that?

posted about 6 years ago

MonLi ‭

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