of course, I don’t think they’d ever keep that from him. Though, I think they chose to tell him when he’s a little older, of course, so he’d understand the concept more. But, Sakurai is a smart kid and he probably got a little confused one day after learning that wait...you can’t (biologically) have a baby with two men...and he might have suspected he was adopted, like Umiko and Takumi, but he looked too much like Sousuke and Rin. He’s seen his baby pictures and everyone always said he looked like Sousuke when he little. Then he visited his Aunt Gou one day and just happened to put two and two together and had a mild panic because generally you have kids with the person you get married to and love right???? And that’s when he decided to go to Sousuke and Rin and ask...he probably started off with “Am I adopted?” bc that was the safer route because he didn’t want to believe that Sousuke might have been with Aunt Gou when he loved Rin. And that’s when Sousuke and Rin decided to tell him the truth (in simple, watered down terms, but still the truth). Sakurai felt much better afterwards. They told him the more technical stuff when he entered high school because he understood more then. And like, even when he learned the truth, it didn’t really change much because he loves both his dads but Aunt Gou almost acts like a mom with him, too, anyway.