The 25-year-old Stanford grad, who now writes for his dad's Fox drama, had been keeping his drinking problem secret. "Two years in and I am more grateful than ever to have a community of support and friends who continue to build me up and hold me accountable," Johnny Lowe wrote on Instagram. Rob Lowe famously struggled with drinking and will celebrate 30 years of sobriety next month. "I have never been more proud. Your hard work is an inspiration. Keep coming back," Rob Lowe commented on his son's post.