I need some clarification here. Idk if this is a spoiler or not, it’s been so long the d...

I need some clarification here. Idk if this is a spoiler or not, it’s been so long the details are mixed up.

But why would he have inherited the same disease that his adoptive dad has, if he’s only related to the woman because that’s his biological mum? How are they even related aside from being adoptive father and son