‘are you decent?’ not morally, but im wearing pants, if thats what youre asking
If Shiro and Keith do turn out to be related then I'm guessing it'll be through Ryou, who'll be like 7 or 10 years older than Shiro for sense-making purposes so he could realistically be Keith's dad. But you know what'd be hilarious? If neither of them actually knew this and they only find out when they discover Ryou mysteriously in space and both react at once and completely separately. See you later space cowboy, good luck explaining this one.