Paternal Family Tree: Capet
Maternal Family Tree: Leonor de Alvim
In 1552 [his father] John Manuel Aviz Prince Portugal [aged 14] and [his mother] Joanna of Austria Princess Portugal [aged 16] were married. She the daughter of [his grandfather] Charles V Holy Roman Emperor [aged 51] and [his grandmother] Isabel Aviz Queen Consort Spain. He the son of John III King Portugal [aged 49] and Catherine of Austria Queen Consort Portugal [aged 44]. They were double first cousins. He a great x 5 grandson of King Edward III of England. She a great x 5 granddaughter of King Edward III of England.
On 2nd January 1554 [his father] John Manuel Aviz Prince Portugal [aged 16] died.
On 20th January 1554 Sebastian King Portugal was born to John Manuel Aviz Prince Portugal [deceased] and Joanna of Austria Princess Portugal [aged 18]. He was named after Saint Sebastian on whose Feast Day he was born. At birth he was heir apparent to the throne of Portugal since his father had died two weeks before his birth. Soon after his birth his mother Joanna of Austria Princess Portugal left Portugal to become Regent of Spain for her father serving in the same capacity for her brother after her father's abdication. She never saw him. Coefficient of inbreeding 20.02%.
On 11th June 1557 [his grandfather] John III King Portugal [aged 55] died. His grandson Sebastian [aged 3] succeeded King Portugal. Sebastian's paternal grandmother Catherine of Austria Queen Consort Portugal [aged 50] acted as Regent during his minority being replaced by Henrique Aviz Cardinal King Portugal [aged 45] when she resigned in 1562.
On 7th September 1573 [his mother] Joanna of Austria Princess Portugal [aged 38] died.
On 4th August 1578 Sebastian King Portugal [aged 24] was killed at the Battle of Alcácer Quibir or the Three Kings. He was succeeded by his great uncle Henrique Aviz Cardinal King Portgal 1512-1580.
Kings Wessex: Great x 16 Grand Son of King Edmund "Ironside" I of England
Kings Gwynedd: Great x 20 Grand Son of Maredudd ab Owain King Deheubarth King Powys King Gwynedd
Kings Seisyllwg: Great x 22 Grand Son of Hywel "Dda aka Good" King Seisyllwg King Deheubarth
Kings Powys: Great x 20 Grand Son of Maredudd ab Owain King Deheubarth King Powys King Gwynedd
Kings Godwinson: Great x 15 Grand Son of King Harold II of England
Kings England: Great x 6 Grand Son of King Edward III of England
Kings Scotland: Great x 14 Grand Son of King Malcolm III of Scotland
Kings France: Great x 7 Grand Son of King John "The Good" II of France
Kings Duke Aquitaine: Great x 20 Grand Son of Ranulf I Duke Aquitaine
Kings Spain: Grand Son of Charles V Holy Roman Emperor
Great x 4 Grandfather: King John I of Portugal 
5 x Great Grandson of King Henry "Curtmantle" II of England
Great x 3 Grandfather: Edward "The Philosopher" I King Portugal Great Grandson of King Edward III of England
Great x 4 Grandmother: Philippa of Lancaster Queen Consort Portugal 
Granddaughter of King Edward III of England
Great x 2 Grandfather: Ferdinand Aviz 2nd Duke Viseu 2 x Great Grandson of King Edward III of England
Great x 4 Grandfather: Ferdinand I King Aragon 
4 x Great Grandson of King Louis IX of France
Great x 3 Grandmother: Eleanor Trastámara Queen Consort Portugal 5 x Great Granddaughter of King Louis IX of France
Great x 4 Grandmother: Eleanor of Alberquerque Queen Consort Aragon 6 x Great Granddaughter of Alfonso II King Aragon
Great x 1 Grandfather: Manuel "Fortunate" I King Portugal 3 x Great Grandson of King Edward III of England
Great x 4 Grandfather: King John I of Portugal 5 x Great Grandson of King Henry "Curtmantle" II of England
Great x 3 Grandfather: Prince John Aviz Constable Portugal Great Grandson of King Edward III of England
Great x 4 Grandmother: Philippa of Lancaster Queen Consort Portugal Granddaughter of King Edward III of England
Great x 2 Grandmother: Beatrice Aviz Duchess Viseu 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandfather: Afonso Aviz I Duke Braganza 6 x Great Grandson of King Henry "Curtmantle" II of England
Great x 3 Grandmother: Isabella of Braganza 7 x Great Granddaughter of King Henry "Curtmantle" II of England
Great x 4 Grandmother: Beatriz Pereira de Alvim
Grandfather: John III King Portugal Great Grandson of John II King Aragon
Great x 4 Grandfather: Ferdinand I King Aragon 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Aragon -2 x Great Grandson of John II King Aragon
Great x 4 Grandmother: Eleanor of Alberquerque Queen Consort Aragon 6 x Great Granddaughter of Alfonso II King Aragon
Great x 2 Grandfather: Ferdinand II King Aragon son of John II King Aragon
Great x 4 Grandfather: Fadrique Enríquez Count Melgar Count Rueda 7 x Great Grandson of Alfonso II King Aragon
Great x 3 Grandmother: Juana Enríquez Queen Consort Aragon 8 x Great Granddaughter of Alfonso II King Aragon
Great x 4 Grandmother: Mariana Fernández Countess Melgar
Great x 1 Grandmother: Maria Trastámara Queen Consort Portugal Granddaughter of John II King Aragon
Great x 4 Grandfather: Henry III King Castile 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Castile Great Grandson of King Edward III of England
Great x 4 Grandmother: Catherine of Lancaster Queen Consort Castile Granddaughter of King Edward III of England
Great x 2 Grandmother: Isabella Queen Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandfather: Prince John Aviz Constable Portugal Great Grandson of King Edward III of England
Great x 3 Grandmother: Isabella Aviz Queen Consort Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandmother: Isabella of Braganza 7 x Great Granddaughter of King Henry "Curtmantle" II of England
father: John Manuel Aviz Prince Portugal 2 x Great Grandson of John II King Aragon
Great x 4 Grandfather: Ernest "The Iron" Habsburg I Duke Austria 15 x Great Grandson of King Alfred "The Great" of Wessex
Great x 3 Grandfather: Frederick "Peaceful or Fat" Habsburg III Holy Roman Emperor 16 x Great Grandson of King Alfred "The Great" of Wessex
Great x 4 Grandmother: Cymburgis Masovia Duchess Austria
Great x 2 Grandfather: Maximilian Habsburg I Holy Roman Emperor 3 x Great Grandson of King Edward III of England
Great x 4 Grandfather: Edward "The Philosopher" I King Portugal Great Grandson of King Edward III of England
Great x 3 Grandmother: Eleanor Aviz Holy Roman Empress 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandmother: Eleanor Trastámara Queen Consort Portugal 5 x Great Granddaughter of King Louis IX of France
Great x 1 Grandfather: Philip "Handsome Fair" King Castile 4 x Great Grandson of King Edward III of England
Great x 4 Grandfather: Philip "Good" Valois III Duke Burgundy 
Great Grandson of King John "The Good" II of France
Great x 3 Grandfather: Charles "Bold" Valois Duke Burgundy 2 x Great Grandson of King John "The Good" II of France
Great x 4 Grandmother: Isabella Aviz Duchess Burgundy Great Granddaughter of King Edward III of England
Great x 2 Grandmother: Mary Valois Duchess Burgundy 3 x Great Granddaughter of King John "The Good" II of France
Great x 4 Grandfather: Charles Bourbon I Duke Bourbon Great Grandson of King John "The Good" II of France
Great x 3 Grandmother: Isabella Bourbon 2 x Great Granddaughter of King John "The Good" II of France
Great x 4 Grandmother: Agnes Valois Duchess Bourbon Great Granddaughter of King John "The Good" II of France
Grandmother: Catherine of Austria Queen Consort Portugal Great Granddaughter of John II King Aragon
Great x 4 Grandfather: Ferdinand I King Aragon 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Aragon -2 x Great Grandson of John II King Aragon
Great x 4 Grandmother: Eleanor of Alberquerque Queen Consort Aragon 6 x Great Granddaughter of Alfonso II King Aragon
Great x 2 Grandfather: Ferdinand II King Aragon son of John II King Aragon
Great x 4 Grandfather: Fadrique Enríquez Count Melgar Count Rueda 7 x Great Grandson of Alfonso II King Aragon
Great x 3 Grandmother: Juana Enríquez Queen Consort Aragon 8 x Great Granddaughter of Alfonso II King Aragon
Great x 4 Grandmother: Mariana Fernández Countess Melgar
Great x 1 Grandmother: Joanna "The Mad" Trastámara Queen Castile Granddaughter of John II King Aragon
Great x 4 Grandfather: Henry III King Castile 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Castile Great Grandson of King Edward III of England
Great x 4 Grandmother: Catherine of Lancaster Queen Consort Castile Granddaughter of King Edward III of England
Great x 2 Grandmother: Isabella Queen Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandfather: Prince John Aviz Constable Portugal Great Grandson of King Edward III of England
Great x 3 Grandmother: Isabella Aviz Queen Consort Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandmother: Isabella of Braganza 7 x Great Granddaughter of King Henry "Curtmantle" II of England
Sebastian King Portugal Grandson of Charles V Holy Roman Emperor
Great x 4 Grandfather: Ernest "The Iron" Habsburg I Duke Austria 15 x Great Grandson of King Alfred "The Great" of Wessex
Great x 3 Grandfather: Frederick "Peaceful or Fat" Habsburg III Holy Roman Emperor 16 x Great Grandson of King Alfred "The Great" of Wessex
Great x 4 Grandmother: Cymburgis Masovia Duchess Austria
Great x 2 Grandfather: Maximilian Habsburg I Holy Roman Emperor 3 x Great Grandson of King Edward III of England
Great x 4 Grandfather: Edward "The Philosopher" I King Portugal Great Grandson of King Edward III of England
Great x 3 Grandmother: Eleanor Aviz Holy Roman Empress 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandmother: Eleanor Trastámara Queen Consort Portugal 5 x Great Granddaughter of King Louis IX of France
Great x 1 Grandfather: Philip "Handsome Fair" King Castile 4 x Great Grandson of King Edward III of England
Great x 4 Grandfather: Philip "Good" Valois III Duke Burgundy Great Grandson of King John "The Good" II of France
Great x 3 Grandfather: Charles "Bold" Valois Duke Burgundy 2 x Great Grandson of King John "The Good" II of France
Great x 4 Grandmother: Isabella Aviz Duchess Burgundy Great Granddaughter of King Edward III of England
Great x 2 Grandmother: Mary Valois Duchess Burgundy 3 x Great Granddaughter of King John "The Good" II of France
Great x 4 Grandfather: Charles Bourbon I Duke Bourbon Great Grandson of King John "The Good" II of France
Great x 3 Grandmother: Isabella Bourbon 2 x Great Granddaughter of King John "The Good" II of France
Great x 4 Grandmother: Agnes Valois Duchess Bourbon Great Granddaughter of King John "The Good" II of France
Grandfather: Charles V Holy Roman Emperor -2 x Great Grandson of Charles V Holy Roman Emperor
Great x 4 Grandfather: Ferdinand I King Aragon 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Aragon -2 x Great Grandson of John II King Aragon
Great x 4 Grandmother: Eleanor of Alberquerque Queen Consort Aragon 6 x Great Granddaughter of Alfonso II King Aragon
Great x 2 Grandfather: Ferdinand II King Aragon son of John II King Aragon
Great x 4 Grandfather: Fadrique Enríquez Count Melgar Count Rueda 7 x Great Grandson of Alfonso II King Aragon
Great x 3 Grandmother: Juana Enríquez Queen Consort Aragon 8 x Great Granddaughter of Alfonso II King Aragon
Great x 4 Grandmother: Mariana Fernández Countess Melgar
Great x 1 Grandmother: Joanna "The Mad" Trastámara Queen Castile Granddaughter of John II King Aragon
Great x 4 Grandfather: Henry III King Castile 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Castile Great Grandson of King Edward III of England
Great x 4 Grandmother: Catherine of Lancaster Queen Consort Castile Granddaughter of King Edward III of England
Great x 2 Grandmother: Isabella Queen Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandfather: Prince John Aviz Constable Portugal Great Grandson of King Edward III of England
Great x 3 Grandmother: Isabella Aviz Queen Consort Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandmother: Isabella of Braganza 7 x Great Granddaughter of King Henry "Curtmantle" II of England
mother: Joanna of Austria Princess Portugal daughter of Charles V Holy Roman Emperor
Great x 4 Grandfather: King John I of Portugal 5 x Great Grandson of King Henry "Curtmantle" II of England
Great x 3 Grandfather: Edward "The Philosopher" I King Portugal Great Grandson of King Edward III of England
Great x 4 Grandmother: Philippa of Lancaster Queen Consort Portugal Granddaughter of King Edward III of England
Great x 2 Grandfather: Ferdinand Aviz 2nd Duke Viseu 2 x Great Grandson of King Edward III of England
Great x 4 Grandfather: Ferdinand I King Aragon 4 x Great Grandson of King Louis IX of France
Great x 3 Grandmother: Eleanor Trastámara Queen Consort Portugal 5 x Great Granddaughter of King Louis IX of France
Great x 4 Grandmother: Eleanor of Alberquerque Queen Consort Aragon 6 x Great Granddaughter of Alfonso II King Aragon
Great x 1 Grandfather: Manuel "Fortunate" I King Portugal 3 x Great Grandson of King Edward III of England
Great x 4 Grandfather: King John I of Portugal 5 x Great Grandson of King Henry "Curtmantle" II of England
Great x 3 Grandfather: Prince John Aviz Constable Portugal Great Grandson of King Edward III of England
Great x 4 Grandmother: Philippa of Lancaster Queen Consort Portugal Granddaughter of King Edward III of England
Great x 2 Grandmother: Beatrice Aviz Duchess Viseu 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandfather: Afonso Aviz I Duke Braganza 6 x Great Grandson of King Henry "Curtmantle" II of England
Great x 3 Grandmother: Isabella of Braganza 7 x Great Granddaughter of King Henry "Curtmantle" II of England
Great x 4 Grandmother: Beatriz Pereira de Alvim
Grandmother: Isabel Aviz Queen Consort Spain Great Granddaughter of John II King Aragon
Great x 4 Grandfather: Ferdinand I King Aragon 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Aragon -2 x Great Grandson of John II King Aragon
Great x 4 Grandmother: Eleanor of Alberquerque Queen Consort Aragon 6 x Great Granddaughter of Alfonso II King Aragon
Great x 2 Grandfather: Ferdinand II King Aragon son of John II King Aragon
Great x 4 Grandfather: Fadrique Enríquez Count Melgar Count Rueda 7 x Great Grandson of Alfonso II King Aragon
Great x 3 Grandmother: Juana Enríquez Queen Consort Aragon 8 x Great Granddaughter of Alfonso II King Aragon
Great x 4 Grandmother: Mariana Fernández Countess Melgar
Great x 1 Grandmother: Maria Trastámara Queen Consort Portugal Granddaughter of John II King Aragon
Great x 4 Grandfather: Henry III King Castile 4 x Great Grandson of King Louis IX of France
Great x 3 Grandfather: John II King Castile Great Grandson of King Edward III of England
Great x 4 Grandmother: Catherine of Lancaster Queen Consort Castile Granddaughter of King Edward III of England
Great x 2 Grandmother: Isabella Queen Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandfather: Prince John Aviz Constable Portugal Great Grandson of King Edward III of England
Great x 3 Grandmother: Isabella Aviz Queen Consort Castile 2 x Great Granddaughter of King Edward III of England
Great x 4 Grandmother: Isabella of Braganza 7 x Great Granddaughter of King Henry "Curtmantle" II of England