Actually, in the case of the open-source culture this is an easy question to answer. It should be understood, however, that projects may be owned by groups. According to the standard open-source licenses, all parties are equals in the evolutionary game. That public redistribution is the fundamental issue is easy to establish.
Custom encourages people to patch software for personal use when necessary.
Custom is indifferent to people who redistribute modified versions within a closed user or development group. It is only when modifications are posted to the open-source community in general, to compete with the original, that ownership becomes an issue. There are, in general, three ways to acquire ownership of an open-source project. One, the most obvious, is to found the project. When a project has had only one maintainer since its inception and the maintainer is still active, custom does not even permit a question as to who owns the project.