 Solution

The output describes complete-linkage clustering: the distance between two current groups is the largest original Jaccard distance between a member of one and a member of the other. Starting with singleton groups, agglomerative hierarchical clustering merges a closest pair at each step. In the merge array, a negative index denotes the original row of that number, and a positive index denotes the group created at that earlier merge. A printed height is the dissimilarity at which the new group forms.

Reading those references recursively gives the following dendrogram construction, with exact heights recovered from the binary profiles:

For example, a cut strictly between $1/2$ and $5/8$ gives four groups: Chad–Nicolas–Frederic–John–Garfield–Fred–Gbenga, Graham–Tim–Philip–Mark, Sauli, and Juliet. A cut strictly between $3/4$ and $7/8$ gives two larger groups. The leaf order is not intrinsic; the merge memberships and heights are. Reflecting branches leaves the dendrogram unchanged in meaning. The zero-height pair indicates identical recorded responses, while high joins indicate comparatively dissimilar profiles. These conclusions depend on the choice of Jaccard distance, which ignores shared negative answers; the dendrogram itself does not establish substantive demographic classes.