If civilization had never fallen, there was a high probability that Senku and Gen wouldn't know each other, much less be married. It wouldn't have been acceptable. Whether or not it was actually acceptable, Senku hadn't cared, they did what they wanted.

"Can't miss him, he's got black and white hair. Genetic condition. He has a necklace like mine." He pulled his necklace out from under his clothes. "Matching band on his wrist too."

He snickered at that. "Lovely...I guess in his own way. He's more devious and a pain in my ass." It was said with a deep level of fondness and exasperation all at once.