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. Both his paternal and maternal grandfather had Spanish ancestry.
