The Maven ecosystem relies heavily on dependencies to provide functionality, but the relationships between these dependencies are not well understood. This paper introduces the concept of dependency families, where a group of dependencies are owned by the same entity and designed to be used together. We develop a method to detect these families using a combination of structural and statistical techniques, and apply it to the Maven Central repository. Our analysis reveals insights into the structure and trends of dependency families, including their size distribution, usage patterns, and version homogeneity. Specifically, we find that most families are composed of a small core of frequently used dependencies alongside many supplemental ones; that releases without code changes are surprisingly prevalent; and that while many dependencies in a family share version numbering, this is not consistent enough for developers to always rely on. Our findings have implications for developers, maintainers, and users of dependencies in the Maven ecosystem.