The present work has repeatedly discussed a number of dynasties that derived much or all of their power from the Norman marches. The following genealogies are intended to clarify a number of details relating to these dynasties (which varied widely in power and status). Constraints of space have prevented the inclusion of a comprehensive survey of frontier families, even for those who may be regarded as great barons. The sheer scope of the inquiry has meant that a number of families have had to be omitted, including the counts of Ponthieu (after William Talvas, d. 1171) and the vidames of Gerberoy and Picquigny, and the families of Avenel, Cayeux, Bailleul, Poix, Chaumont, Fontenay, La Ferté-Macé, Leicester, Longchamps (except for the Baudemont branch), Nonant, Rémalard, Saint-Valéry and Vautorte. The genealogies of several families discussed below have already been addressed by other historians but are reconsidered here for corrections or additions (e.g. Baudemont, Crispin, l'Aigle, Fougères, Mayenne and Talvas). The chronological scope of the reconstructions necessarily varies from family to family. The evidence often precludes reconstruction of any sort in the early and middle decades of the twelfth century but some are continued here into the mid-thirteenth century where appropriate (for instance, until the failure of male heirs leading to division or substitution of a new agnatic line).

The historian wishing to reconstruct central medieval lineages faces several problems.