To be fair, none of the children has even once met the man we asssumed to be "the father" since he got arrested by the cops. So, it could be that the man was not the father, but rather someone he hired, he ordered, or he convinced to impersonate him for some reason somehow🤔
His brother could be the culprit behind the serial attack on abusive parents, but I doubt he was the one who pushed Kanon nor the one who locked the children in the basement