We introduce three data visualization projects related to systems genetics and addiction research. Historically, the challenge of biology research has been one of data collection. However, as measurement becomes easier, the challenge shifts towards data sensemaking. Here, researchers are asking questions about the relationships between genes, traits, and the microbiome, using visualization for data exploration. This work has implications for visualization of high-dimensional data in other domains, as it shows how statistical methods can support visualization filtering, aggregation, and information hierarchies to explore dense data.