I'm not sure specifically which 'ash studies king gene fanfiction' is popular. You could try searching on major fanfiction platforms like Archive of Our Own or FanFiction.net. There might be a variety of stories related to it there.
Chapter 34 is the strongest chapter-level answer because it starts from Seeing that the public sentiment wasn't quite right, Su Yinwan felt... and follows through on Now that Lili is misunderstood, they start to kick us while we're down."....
Chapter 940, "When Did the River Moon First Illuminate People? [Extra · River Moon Chapter]", is the clearest early answer because it turns Shang Shuyue's situation into a concrete plot event.
If you want the clearest chapter reference, go to Chapter 76. Early on, Thinking of this, the aunt repeatedly praised, "Girl, hearing your words...; later, the chapter leans on I'll go back and tell this to my child; he will definitely be motivated to....
Chapter 51 is the strongest chapter-level answer because it starts from Oh, okay." After uttering two syllables indifferently, Jiang Li bent down... and follows through on If I opened a bar here, wouldn't I become a savior?" Jiang Yan was....
The best chapter pointer here is Chapter 15, "The Autistic Teen Jiang Shixu". It opens with Jiang Shixu woke up from those nightmares filled with blood and darkness,... and closes on Since she didn't move, Jiang Shixu also stayed put, and the kitchen, which....
Look to Chapter 58 for the clearest answer. It begins with Facing Jiang Yan's triple barrage of questions, Jiang Li's only response..., keeps building through After a long while, she yawned indifferently and said, "I didn't pick up..., and lands on By ten o'clock, Jiang Yan was still wandering.
Look to Chapter 28 for the clearest answer. It begins with The next evening, Jiang Yan drove home seething with rage., keeps building through Before he even entered the dining room, he shouted angrily, "Lili, you did..., and lands on Lili then kicked his knee hard..
If you want the clearest chapter reference, go to Chapter 18. Early on, In the corner, a girl in a black dress sat quietly, holding a glass of...; later, the chapter leans on Her serene yet cold temperament, along with her exquisitely beautiful....
Look to Chapter 22 for the clearest answer. It begins with Hearing this, Su Yinwan looked at Shang Shaojing with a face full of..., keeps building through Shang, but it's not necessary;
If you want the clearest chapter reference, go to Chapter 16. Early on, Just as the words fell, Jiang Shixu swiftly cast his eyes downward.; later, the chapter leans on His eyelashes were very long; when they fell, they could cast a small....