Responses
Probably because they want purebred pufferfish. A child between the dolphin father and the pufferfish mother would be a half-breed. Must've used contraceptives to prevent her from having babies with the dad or maybe they aborted or adopted out those babies.
they like the toxin in pufferfish body so obviously no condom,or maybe author just didn't think about that part because this is yaoi ,their parent are straight.
i was wondering the silver hair psycho they have their partner and kid but why no kid with the Pufferfish i mean his mother with the twin's father .i am sure the twin's father cum inside his mother