His parents' divorce was the reason for his turn to misconduct.
The son's reason for turning to delinquency was his parents' divorce.
His parents' divorce was the catalyst for the son's bad behavior.
「非行」は「misconduct」、「delinquency」といいます。
「非行に走る」は「turn to misconduct」、「turn to delinquency」です。
「〜がきっかけ」はよく「chance」になりますが、この場合は「reason(理由)」や、「catalyst(刺激)」がいいと思います。
His parents' divorce was the reason for his turn to misconduct.
彼が飛行に走ったのは、親の離婚がきっかけでした。
The son's reason for turning to delinquency was his parents' divorce.
息子が非行に走ったのは、親の離婚がきっかけでした。
「非行」は「bad behavior」とも訳せます。
His parents' divorce was the catalyst for the son's bad behavior.
親の離婚が息子が非行に走った理由となった。