He married Sancha Fernández de Lara, daughter of Fernando Núñez de Lara and wife Mayor González, without any documented issue.
He had, however, a bastard son by an unknown woman named Sancho Fernandes de Serpa, who was a Prior at Santo Esteban de Alfama,
but had illegitimate issue, being the ancestor of the de Serpa family.
In a study from the Spanish historian Faustino Menéndez-Pidal de Navascués,[4] the infante Fernando should have used a Coat of Arms representing a Wyvern (Serpe in Portuguese), the symbol of his Lordship of Serpa, in south Alentejo, with a border where, alternately, are represented the arms of Portugal (paternal ancestry) and those of Castile (maternal ancestry).
