My personal tinfoil hat theory is that Yuu is actually Akira's grandfather, Nozomu is actually his father, but also his brother, because Nozomu raped his mother, and that's why Akira barely has any memories of her -- Nozomu and his then-girlfriend took his son and raised him as his brother (because technically true).
Do I have any textual basis? No.
Is it consistent with Nozomu's character? Kinda.
Am I right? Probably not.