Senku's father Byakuya was one of the few people who survived. While all of the couples were shown to have offspring, it wasn't explicitly shown that Byakuya and Lillian had children, too.
It might be because of the drawing style, but Kohaku and Ruri do seem to have a very similar appearance as Lillian (although thousands of years have already passed...).
So, is it known or at least hinted that they did have offspring?
Heavy manga spoilers ahead read at your own risk:
In manga ch 45, Kohaku asks if they are related to which Senku answers
that he and Byakuya are NOT blood related BUT they (he and the villagers)
are hundreds of generations apart so it doesn't matter.
Yes they had children, no they are not related to Senku.
(Note that they don't specifically show that Byakuya and Lillian were together but
there was the already married couple and they showed Connie and Shamil getting married so most
probably Byakuya ended up with Lillian)
I think it basically implies they did. Kohaku and Yuri look like Lillians bloodline. Eventhe former village chief looks like he is too. The other characters. None of the other 4 looked like they would have kids that look like that. The girl named shovel is the offspring of the Russian and the daughter. Never exactly said how soon it was Lillian died after the Russian. It seemed like some years passed between the daughter dying and then Russian and finally Lillian. Yeah whoever thinks she's not going to hook up with the only guy left on earth or is she just going to wait till one of those kids grows up? Hopefully that's a joke. By saying they aren't related because of being generations apart just means that there has been so many years of offspring I believe 3700 was it 3700 years or something that you wouldn't share much anymore. You look like a foreigner, well to someone who is Japanese an American like Lillian would be a foreigner to them and same with Russian and whatever else there was. They really have a tiny village for seriously having that many years to make kids. His dad says this is what he leaves for Senku. So he's making a village to help him save the world. Lillian totally had a thing for Senkus dad, If I had to choose I would go with they definitely had kids together.
No. They didn't have children. Senku's father was an old Japanese man and Lillian was a young American Singer. By all perspectives, there was no way for these two to possibly get together in a sexual way. She has standards too bloody hell. More evidence was the hair color of the villagers were mostly blonde and brown which meant they were all of pure European descent. Even senku admitted Kohaku looked like a foreigner. If she had Japanese blood, she would not look like one at all. Senku's father was mostly just an old wise man that led the children as the adults died. Furthermore there's no evidence they even had children. The young singer died without childbearing. And even though senku said that even IF the descendants and his father were related somehow, the generations apart would make it not matter anymore. But it was just an IF. Evidence doesn't show that they had any children at all. Notice the scientists were all Europeans? the whole show is pretty much a Japanese boy showing off science to the descendants of Europeans who literally invented that science and spread it around the world. It's a means of portraying a false image of Japanese being somehow better than Europeans in terms of innovations.
