Jumping genes are double-edged sword: By copying and integrating themselves into other parts of the genome these so-called transposons can lead to a variety of genetic disorders such as haemophilia or breast cancer. On the other hand the mobile DNA bits can create new genes and new gene expression programs. This is crucial for maintaining high genetic variability and adaptability to environmental changes. Scientists from the Max Planck Institute of Immunobiology and Epigenetics Freiburg in collaboration with the University of Freiburg have now found that an enzyme called DHX9 can neutralize the harmful structures formed by transposons and effectively increase the tolerance of the genome to include these jumping genes. By understanding this process better scientists can devise better therapies for diseases caused by transposons while retaining their evolutionary advantage.