Shiggy made a mistake.

So basically Deku and Enji are dating but the TodoSiblings are quadruplets and Enji is younger and Rei had them @ 17 So as not weird as possible. Deku is 16, but that's the age'O'consent in Japan so legal. And DAD 4 2 au so AFO is Deku and Tomuras dad. Tomu is adopted and chaos ensues.