Comedian Sarah Silverman, who routinely courts controversy with her edgy humor, recently made an attention-getting statement of a more intimate nature: because of her personal and family history of depression, she declared that she would not have biological children, to avoid passing her mental problems to the next generation. “I don’t want kids,” she said on The Conversation with Amanda de Cadenet. “I know that I have this depression and that it’s in my family. Every family has their stuff but, for me, I just don’t feel strong enough to see that in a child.” …

Atlantic writer David Dobbs has called such genes “orchid genes.” Like the finicky flowers, they thrive and outshine ordinary plants when grown in the perfect conditions, but otherwise rapidly wilt and die. In contrast, he describes “dandelion genes,” which allow healthy development, whether the setting is harsh or bountiful.

Some of the genes involved in risk for attention deficit hyperactivity disorder (ADHD), addiction and depression seem to share this quality, leading to vulnerability if early life is difficult but otherwise providing advantages. A recent study found also that people who had genes associated with better memory — a powerful aid to learning and intelligence — were more likely to suffer post-traumatic stress disorder after trauma, compared with those without the same genetic variants. People with better memories had more flashbacks.