Vectorization of viruses provides the approach to exploit the remarkable viral capabilities of delivering genetic material to host cells. In the past decade, viral vector mediated gene therapy has emerged as a promising therapeutic modality for multiple inherited and acquired human diseases. Following just a single application, GT is capable of providing curative treatment or achieving long-lasting therapeutic benefits, which fundamentally distinguishes itself from traditional medicine. For the last four decades, retrovirus-based genetic intervention has been the major player in the field of GT, and multiple lentiviral/γ-retroviral vector-mediated GT products have been approved for treating various pathological conditions, including immunodeficiency, blood disorders and neurometabolic disorders. However, the early development of GT had been turbulent, with unexpected devastating effects exposed linked to the genotoxicities associated with retroviral semi-random genomic insertion. Here we talk about how the iterative vectorization processes taming the retroviruses, enabling them to become the foundation of modern gene therapy. And we will also take an evolutionary perspective to understand and perceive how retroviruses shaped us in the distant past.