There is no quality control for Predator EU stuff, so there's actually a couple different accounts of their sexuality

But my favorite (and most popular iirc) is the one where the sequential hermaphroditism is triggered by very high social status, e.g. they've hunted enough and claimed enough honor and experienced enough triggering phereomonal and neurological events that they become female, and can now give birth, and naturally become members of the ruling class in doing so