Researchers can determine the consequences of gene expression on the functional properties of structural proteins by either switching genes on and off and observing the consequences in the secreted proteins, or by observing the function of the proteins produced in different organisms with varying levels of expression of a particular gene . Indeed, using such approaches has informed us how and why certain genes cause specific ailments in humans and other animals . Progress has been recently made into our understanding of spider silk genes and their expression patterns [7–11]. Likewise, significant insights have been gained on silk production, spinning, and its engineering [11–15]. However, because no single study has holistically examined the consequences of gene expression on protein structure and silk functional properties, it is not known why spiders spin silks with such exceptional properties and, more importantly, why silk properties vary so much between and within individual spiders . Experimentally switching silk related genes on and off within individual spiders is not yet achievable, so observing the function of silk proteins in different spiders with varying levels of expression of particular genes appears the best way forward.