Son of Francisco Xavier de Castro de Avelar Froes, great-grandson of a first cousin of the first Viscount and first Count of Avelar, great-great-great-great-great-great-great-great-great-grandson of the first Count of Gavia la Grande Nobleman of Coat of Arms of de los Ríos (timber) with crown of Count and first Viscount of los Castellones Nobleman of Coat of Arms of de los Ríos (timber) with crown of Viscount and great-great-grandson of the first Count of Burnay Nobleman of New Coat of Arms of Burnay and of the President of the Republic Manuel de Arriaga, and second wife, of whom he was second civil husband, Maria Teresa Salema de Sande e Castro Vejarano. Has two half-siblings from his father's first marriage with Isabel Maria Guimarães Serôdio d' Orey: Maria Teresa d' Orey de Castro Froes
(b. 20 Jan 1980) and Pedro Vitorino d' Orey de Castro Froes (b. 18 Apr
1981). Has three half-siblings from his mother's first marriage with
José Manuel Baptista Fino: Martim, Maria da Pureza and Frederico. Has
another half-sibling, natural daughter of his mother, Patrícia Salema
de Sande e Castro Fino. Both his paternal and maternal grandfather had Spanish ancestry.