Currently, the design, deployment and refinement of new network architectures is a manual, ad-hoc and time-consuming process. We present the design, implementation and evaluation of the Genesis Kernel, a programming system that automates the life cycle process for the creation, deployment, management, and architecting of network architectures. We discuss our experiences in building a spawning network that is capable of creating distinct virtual network architectures on-demand. The Genesis Kernel is based on a methodology that allows a child virtual network to operate on top of a subset of its parents network resources and in isolation from other spawned virtual networks. We show through experimentation how a number of diverse network architectures can be spawned and architecturally refined. These spawned network architectures include a parent network that supports IP forwarding, and interior and exterior routing. We discuss how two child networks based on Cellular IP and Mobiware architectures can be spawned on the parent network to support wireless access to data and continuous media services, respectively.