The present invention relates to systems, apparatus, and methods of modeling a hierarchical object relationship in a hypertext mark-up language (HTML) context. In some embodiments, a probabilistic determination is made of parentage of content objects being requested over a communications system. In certain embodiments, the content objects are intercepted by a proxy server as part of a prefetching system. When parentage is uncertain, a system may identify a plurality of nodes that are potential parent/root nodes for the content object, associate a likelihood with each parent/root node, and establish a potential parent/root node as the parent for the purposes of a prefetching. Various embodiments use referrers where reliable, supplemented or supplanted by other techniques (e.g., “rootable” URL determinations) to model the object hierarchies and parent/root relationships.