Inside the cell nucleus, genes must be turned on and off with precision to regulate biological processes. The first models of gene regulation were developed in the 1960s, yet modern science continues to uncover new layers of control. A new study involving researchers from the Institute of Science and Technology Austria (ISTA), the Institut Pasteur and Princeton University, published in PNAS, suggests that genes obey an optimal switching principle—random at any given moment, yet precise on average.