It makes sense. So it's like this then, qiurang's father like mc's father but mc's father like adoptive brother's father. That's why mc's father give attention more to the adoptive brother than his own son. And cuz mc look like his father, he got sexual harassment by qiurang's father. Then, got memory loss due to trauma. Like father like son. They also have love triangle. Qiurang > He wei (mc) > adoptive brother. But the difference between the father and the son is the adoptive brother like qiurang so he's not straight ╮( ̄▽ ̄)╭.

another crazy theory, what if the memory the mc had wasn't him truly but was the adopted brother getting assaulted by mc's dad which goes well with my another theory the mc's dad was inlove with the adopted brother's father
maybe this is far fetched theory but i have read so many yaoi Chinese web novels with a lot of weird twists like this :D Maybe i should cut off reading them a little bit