In Father of the Magic Way, why doesn't Jiang Cheng admit that Ling Jin is the child of his senior sister?

I met Ling Jin before I went to the Great Brahma Mountains, but I didn't know. Later, Ling Jin called out his uncle and realized that he was the son of an old friend and was not jealous. Because he didn't recognize Jiang Cheng, he couldn't let Jiang Cheng recognize himself because of the death of the teacher elder sister. Riverside has no envy and regrets that he scolded the teacher elder sister's child. Ling Jin is the only son of the teacher elder sister, who was once the closest person to Wei Ying in this world. But people are not vegetation after all. Whatever the reason, Ling Jin has become an orphan, and he has an unshirkable responsibility. So, since knowing Ling Jin's identity, Wei Ying has been taking care of him. Whether it's to stop the dancing goddess or to shift the curse from Ling Jin. Even, Ling Jin stabbed him directly, and Wei Ying didn't complain, just laughed it off.

I guessed right, so when Jin Lingju stabbed him with a sword, he didn't hide, but was blocked by Lan Zhan. He said that he couldn't face Jiang Cheng because he didn't know before, and he didn't want to talk to Jiang Cheng and Lan Zhan, so he hid without saying anything, secretly annoyed and blamed himself.

Because after all, Wei Wuxian died once, and just came back, his brain couldn't react to many things. He knows Jiang Cheng and Lan Zhan, but after all, he has been dead for more than ten years, and his brain circuit has not responded so quickly. He began to slowly recall his life with Jiang Cheng and his sister. After all, the relationship with Jiang Cheng has broken down, which makes him doubt his life. After all, he is too emotional to accept the break between brothers, and he is bent on protecting his current identity, and he doesn't want Lan Zhan to recognize himself. He began to recall the teacher elder sister Jiang Cheng by the river, and they were still in grief. Just as passers-by directly exposed Ling Jin's identity, his brain suddenly changed, and he regretted saying those words to Ling Jin. After all, in addition to the children of the teacher elder sister, Jin of Lanling may also be Jin Guangyao's child, and he certainly could not judge at that time.

When I was in Brahma, I knew that Ling Jin was a member of Guinness in Lanling. He didn't like Guinness in his understanding of Lanling, so I taught the boy a lesson. Who knew what a coincidence! It turned out to be the teacher elder sister's child. Although I didn't like him at first, once I knew his identity, I paid special attention to him and protected him. I used to think I was a stone, but I didn't expect to be a man without vegetation after all. He sighed from the heart and agreed with this sentence.