Cardassian-Bajorans hybrids? Two of them in fact - Ziyal, and Dukat's other half-Bajoran child, with Mika the cultist - which apparently get conceived naturally and even come as a surprise?
Canonically, the ancient Hebitians seem to have visited both Bajor and Cardassia Prime. The coffee table art book, "New Worlds, New Civilizations" has a story that suggests newly found artifacts from the Hebitians suggested they were progenitors of both r
aces, ie. a common ancestor.