Responses
I believe they didn’t know. At least Takezou didn’t. Their father married Takezou’s mother after he was born, so on paper they are not supposed to be related by blood. The report shook Takezou to the core and confirmed the “doubt” that Shinobu had been carried along about their relationship.
Oooh thanks, I thought they knew all along
They didn't have a doubt about being brothers, so what did the report change?