How should we understand taking rebirth?
When we ask the older generation, they take the teachings literally and say, for example, that if we do something very negative, we will be reborn in the lower realms. For the younger generation, however, it is easier to speak of states of mind, understanding these realms as different kinds of consciousness. The Karmapa replied that both understandings⎯as a mental state and as a place of taking birth⎯are possible. Good and bad rebirths depend on the karma we have created, and further, not only are we reborn in one of the six realms, but there are also the differences of our particular place of birth, the surroundings, the type of body we have, our mental state, and so forth.
“When we speak of the three lower realms,” the Karmapa explained, “they can be understood from the point of view of their cause and of their effect. Their cause is a mental state.” For example if someone becomes very angry, this can propel them into a rebirth in a hell realm. We usually speak of the hot hells, he said, and the mental state of anger feels as if we are burning, so it is like being in hell. Similarly, the hungry ghosts suffer from having huge desires and great miserliness. Their throats are said to be as thin as a needle and their stomachs as big as a mountain. This can be read as a metaphor for the mental state of needing a lot and being unable to give. So the answer to your question, the Karmapa concluded, is that taking rebirth is both: a mental state as a cause and a particular kind of rebirth as a result.
~Karmapa: Meeting with the Younger Generation of Tibetans in Switzerland