How did jin become devil jin?

Answer:
At 5 years old, Kazuya Mishima was thrown off a cliff by his father, Heihachi. Wanting revenge, he sold his soul to the Devil. So therefore, Kazuya had the devil inside of him/ the devil gene. During The King of Iron Fist 2 (Tekken 2) Jun and Kazuya were intimate, and conceived Jin. Because Kazuya had the devil gene, Jin had it, thus he becomes Devil Jin.
First answer by Xsmexyyx. Last edit by Xsmexyyx. Contributor trust: 0 [recommend contributor recommended]. Question popularity: 2 [recommend question].