The informational capacity of a hereditary polymer is constrained not only by its chemical alphabet but also by its structural organization and readout mechanisms. Canonical duplex DNA encodes information primarily through pairwise base complementarity, yielding well-characterized limits on information density and error tolerance. In this work, I develop an information-theoretic framework for Q-DNA, a canonical tetra-stranded hereditary polymer, and show that tetra-strand coupling enables non-pairwise, multi-body encoding schemes. I derive upper bounds on information per unit length under structural and readout constraints, compare Q-DNA to DNA, RNA, and XNA systems, and identify regimes in which tetra-stranded heredity may trade encoding density for robustness—or vice versa. This analysis renders Q-DNA information capacity quantitatively testable and places tetra-stranded heredity within a rigorous communication-theoretic framework.