Arnold has been married multiple times. While details are limited to protect privacy, it's known she experienced both the joys and challenges of marriage and raising a family.

Arnold is the mother of three sons. Balancing her demanding career with motherhood has been a significant part of her life. She has spoken about the difficulties women in STEM face in balancing work and family responsibilities.

Frances Arnold was diagnosed with cancer and underwent treatment. She discussed her cancer journey openly, highlighting both the challenges and her gratitude for the support she received. She has been an advocate for cancer research.

As a young adult, Arnold demonstrated independence and a desire to explore the world, hitchhiking through Europe. This early experience shaped her worldview and instilled a sense of adventure that has influenced her approach to science.

Arnold has spoken candidly about the challenges of balancing a high-powered career with family life, particularly as a woman in a male-dominated field. Her experiences have made her a strong advocate for gender equality and work-life balance.