All of the students of Class 2-2 were having gym class. Chen watched suspiciously as Luhan and Sehun were talking. When Sehun left, Chen approached Luhan.

“Hey Luhan, you and Sehun really look alike. Are you sure you guys aren’t twins separated at birth? You know, you should interrogate your mother because I think she fabricated the story about your birth.” Chen said.

“Don’t be stupid, Chen. The possibility of me being an actual twin of Sehun is one in a million. There’s no way we came from the same mother and were separated in different countries and 16 years later, we’re reunited at the same academy.” Luhan replied. “Speaking of twins, I forgot how they are formed. Do you know how?”

“Are you joking? You didn’t just ask me a question about Biology.”

“Oh, you failed the last test. Sorry, I forgot.”

“Maybe you can ask Chanyeol. He got an A. Yeah, unpredictable. Who would’ve thought that inside that nutcase is a potential medical practitioner?”

“Don’t underestimate the brain power of a crazy. I’ll ask him later.”

---

“Hey Chanyeol, heard you got an A on Biology.” Luhan, called out to Chanyeol before he got to leave the class.

“Yeah, I did. Impressive huh?” Chanyeol said as he raised his eyebrows. “What can I do for you?”

“I was just curious about how twins are formed. I’m too lazy to open up the text book.”

“Sure. Identical or fraternal?”

“They’re formed in different ways? Both then.”

“Yup. Identical twins are formed when the cells from a fertilized ovum or a morula splits into two embryos. Only one and ovum are involved in the process of fertilization. The two embryos then develop into two separate foetuses in the uterus. Each foetus has its own umbilical cord but shares the same placenta. Since the twins originate from one embryo, they are therefore identical in every aspect. Siamese twins are identical twins which did not separate completely during embryonic development.”

“And fraternal?”

“Fraternal twins are formed when two ova are released at the same time, one from each ovary. Each ovum is then fertilized by a . As a result, two zygotes are formed and develop into two separate embryos. Both embryos develop into two foetuses each with its own placenta and umbilical cord. Since the twins originate from two ova and two , they have different genetic constitutions and physical characteristics.”

“Woah dude, you memorized all of that? You’re like a textbook. I didn’t know you were this smart.”

“Thank you, thank you. Don’t despair Luhan, because you are the pilot of your own life. I gotta get to class. You don’t get smart by being late, you know? Later.”