Выпуск 1317. Скрывал внучку 13 лет?

Before his death, the man stunned his mother with a confession: it turns out that he had been registered as a father for 13 years. However, the man had doubts about his relationship with the girl and instructed his mother to conduct a DNA test with her granddaughter. However, the girl's mother was surprised when the would-be mother-in-law found her, as she believed the woman to be deceased. Why did the son erase his mother from his life? And how could the grandmother have been unaware of her granddaughter for 13 years?