In 1311 [her father] John Brabant III Duke Brabant 1300-1355 (age 10) and [her mother] Marie Évreux Duchess of Brabant (age 8) were married. She the daughter of Louis I Count Évreux 1276-1319 (age 34) and Margaret Artois Countess Évreux 1285-1311 (age 26). He the son of John "Peaceful" Reginar II Duke Brabant 1275-1312 (age 35) and Margaret Plantagenet Duchess Brabant 1275-1333 (age 35). They were second cousins. He a grandson of King Edward "Longshanks" I of England. She a great x 2 granddaughter of King Henry III of England. 
On 27 Oct 1312 [her grandfather] John "Peaceful" Reginar II Duke Brabant 1275-1312 (age 37) died. His son [her father] John Brabant III Duke Brabant 1300-1355 (age 12) succeeded III Duke Brabant.
In 1322 Joanna Reginar Duchess Brabant was born to John Brabant III Duke Brabant 1300-1355 (age 21) and Marie Évreux Duchess of Brabant (age 19). She a great granddaughter of King Edward "Longshanks" I of England. Coefficient of inbreeding 3.60%.
In 1334 William Hainault II Count Hainault (age 27) and Joanna Reginar Duchess Brabant (age 12) were married. She the daughter of John Brabant III Duke Brabant 1300-1355 (age 33) and Marie Évreux Duchess of Brabant (age 31). He the son of William Hainault I Count Hainault III Count Avesnes III Count Holland II Count Zeeland (age 48) and Joan Valois Countess Zeeland Holland Avesnes and Hainault (age 40). They were half second cousins. He a great x 5 grandson of King Henry "Curtmantle" II of England. She a great granddaughter of King Edward "Longshanks" I of England.
On 31 Oct 1335 [her mother] Marie Évreux Duchess of Brabant (age 32) died.
On 07 Jun 1337 [her father-in-law] William Hainault I Count Hainault III Count Avesnes III Count Holland II Count Zeeland (age 51) died. His son [her husband] William Hainault II Count Hainault (age 30) succeeded II Count Hainault. Joanna Reginar Duchess Brabant (age 15) by marriage Countess Hainault.
On 26 Sep 1345 [her husband] William Hainault II Count Hainault (age 38) died. His sister [her sister-in-law] Margaret Hainault Holy Roman Empress (age 33) succeeded II Countess Hainault. Louis Wittelsbach IV Holy Roman Emperor (age 63) by marriage Count Hainault.
On 02 Feb 1354 Robert Dampierre (age 31) and [her former sister-in-law] Isabelle Hainault (age 31) were married. She the daughter of William Hainault I Count Hainault III Count Avesnes III Count Holland II Count Zeeland and Joan Valois Countess Zeeland Holland Avesnes and Hainault. He the son of John Dampierre I Marquis Namur 1267-1330 and Marie Artois. They were second cousins. He a great x 2 grandson of King Henry III of England. She a great x 5 granddaughter of King Henry "Curtmantle" II of England. 
On 05 Dec 1355 [her father] John Brabant III Duke Brabant 1300-1355 (age 55) died. His daughter Joanna Reginar Duchess Brabant (age 33) succeeded as Duchess Brabant.
In 1361 [her former sister-in-law] Isabelle Hainault (age 38) died.
On 01 Nov 1406 Joanna Reginar Duchess Brabant (age 84) died.
Paternal Family Tree: Reginar aka Percy
Maternal Family Tree: Margaret Geneva Countess Savoy 1180-1252
Descendants Family Trees:
Kings Wessex: Great x 9 Grand Daughter of King Edmund "Ironside" I of England
Kings England: Great Grand Daughter of King Edward "Longshanks" I of England
Kings Scotland: Great x 7 Grand Daughter of Malcolm III King Scotland
Kings Franks: Great x 5 Grand Daughter of Louis VII King Franks
Kings France: Great Grand Daughter of Philip "Bold" III King France
Great x 4 Grandfather: Henry Reginar VIII Duke Lower Lorraine I Duke Brabant
Great x 3 Grandfather: Henry Reginar II Duke Brabant 1207-1248 3 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandmother: Maud Metz 2 x Great Grand Daughter of King William "Conqueror" I of England
Great x 2 Grandfather: Henry Reginar III Duke Brabant 1230-1261 4 x Great Grand Son of King William "Conqueror" I of England
Great x 1 Grandfather: John Reginar I Duke Brabant 1253-1294 5 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandfather: Odo III Duke Burgundy 3 x Great Grand Son of King William "Conqueror" I of England
Great x 3 Grandfather: Hugh IV Duke Burgundy 1213-1272 4 x Great Grand Son of King William "Conqueror" I of England
Great x 2 Grandmother: Adelaide Burgundy Duchess Brabant 1233-1273 5 x Great Grand Daughter of King William "Conqueror" I of England
Great x 4 Grandfather: Robert Capet III Count Dreux 1185-1234
Great x 3 Grandmother: Yolande Capet Duchess Burgundy 1212-1248
GrandFather: John "Peaceful" Reginar II Duke Brabant 1275-1312 6 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandfather: Guy Dampierre
Great x 3 Grandfather: William Dampierre II Count Flanders 1196-1231
Great x 4 Grandmother: Mathilde Bouron
Great x 2 Grandfather: Guy Dampierre Count Flanders 1226-1305 4 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandfather: Baldwin IX Count Flanders VI Count Hainault 1171-1205
Great x 3 Grandmother: Margaret II Countess Flanders 1202-1280 3 x Great Grand Daughter of King William "Conqueror" I of England
Great x 4 Grandmother: Marie Blois Countess Flanders -1204
2 x Great Grand Daughter of King William "Conqueror" I of England
Great x 1 Grandmother: Margaret Dampierre Duchess Brabant 1253-1285 5 x Great Grand Daughter of King William "Conqueror" I of England
Great x 4 Grandfather: William "Red" Béthune II Lord Bethune
Great x 3 Grandfather: Robert VII Lord Bethune
Great x 2 Grandmother: Mathilde Bethune
Father: John Brabant III Duke Brabant 1300-1355 Grand Son of King Edward "Longshanks" I of England
Great x 4 Grandfather: King Henry "Curtmantle" II of England Grand Son of King Henry I "Beauclerc" England
Great x 3 Grandfather: King John "Lackland" of England Son of King Henry "Curtmantle" II of England
Great x 4 Grandmother: Eleanor of Aquitaine Queen Consort Franks and England
Great x 2 Grandfather: King Henry III of England Son of King John "Lackland" of England
Great x 4 Grandfather: Aymer Angoulême I Count Angoulême 1160-1202
Great x 3 Grandmother: Isabella of Angoulême Queen Consort England
Great x 4 Grandmother: Alice Courtenay Countess Angoulême -1218
Great x 1 Grandfather: King Edward "Longshanks" I of England Son of King Henry III of England
Great x 4 Grandfather: Alfonso Barcelona II Count Provence 1174-1209
Great x 3 Grandfather: Raymond Berenguer Provence IV Count Provence 1198-1245
Great x 2 Grandmother: Eleanor of Provence Queen Consort England
Great x 4 Grandfather: Thomas Savoy I Count Savoy
Great x 3 Grandmother: Beatrice Savoy Countess Provence 1198-1267
GrandMother: Margaret Plantagenet Duchess Brabant 1275-1333 Daughter of King Edward "Longshanks" I of England
Great x 4 Grandfather: Ferdinand II King Leon 1137-1188
Great x 3 Grandfather: Alfonso IX King Leon 1171-1230
Great x 4 Grandmother: Urraca Burgundy Queen Consort Leon 1148-1211
Great x 2 Grandfather: Ferdinand III King Castile III King Leon Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Alfonso VIII King Castile 1155-1214
Great x 3 Grandmother: Berengaria Ivrea I Queen Castile 1179-1246 Grand Daughter of King Henry "Curtmantle" II of England
Great x 4 Grandmother: Eleanor Plantagenet Queen Consort Castile 1161-1214 Daughter of King Henry "Curtmantle" II of England
Great x 1 Grandmother: Eleanor of Castile Queen Consort England 2 x Great Grand Daughter of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Alberic Dammartin
Great x 3 Grandfather: Simon Dammartin
Great x 4 Grandmother: Mathilde Clermont
Great x 4 Grandfather: William Montgomery IV Count Ponthieu 1179-1221
Great x 3 Grandmother: Marie Montgomery Countess Ponthieu 1199-1250
Great x 4 Grandmother: Alys Capet Countess Ponthieu 1160-1220
Joanna Reginar Duchess Brabant 1322-1406 Great Grand Daughter of King Edward "Longshanks" I of England
Great x 4 Grandfather: King Philip II of France 2 x Great Grand Son of King William "Conqueror" I of England
Great x 3 Grandfather: Louis "Lion" VIII King France 3 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandmother: Isabelle Flanders Queen Consort France 1170-1190
Great x 2 Grandfather: King Louis IX of France Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Alfonso VIII King Castile 1155-1214
Great x 3 Grandmother: Blanche Ivrea Queen Consort France Grand Daughter of King Henry "Curtmantle" II of England
Great x 4 Grandmother: Eleanor Plantagenet Queen Consort Castile 1161-1214 Daughter of King Henry "Curtmantle" II of England
Great x 1 Grandfather: Philip "Bold" III King France 2 x Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Alfonso Barcelona II Count Provence 1174-1209
Great x 3 Grandfather: Raymond Berenguer Provence IV Count Provence 1198-1245
Great x 2 Grandmother: Margaret Provence Queen Consort France 1221-1295
Great x 4 Grandfather: Thomas Savoy I Count Savoy
Great x 3 Grandmother: Beatrice Savoy Countess Provence 1198-1267
GrandFather: Louis I Count Évreux 1276-1319 3 x Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Henry Reginar VIII Duke Lower Lorraine I Duke Brabant
Great x 3 Grandfather: Henry Reginar II Duke Brabant 1207-1248 3 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandmother: Maud Metz 2 x Great Grand Daughter of King William "Conqueror" I of England
Great x 2 Grandfather: Henry Reginar III Duke Brabant 1230-1261 4 x Great Grand Son of King William "Conqueror" I of England
Great x 1 Grandmother: Maria Reginar Queen Consort France 1256-1321 5 x Great Grand Daughter of King William "Conqueror" I of England
Great x 4 Grandfather: Odo III Duke Burgundy 3 x Great Grand Son of King William "Conqueror" I of England
Great x 3 Grandfather: Hugh IV Duke Burgundy 1213-1272 4 x Great Grand Son of King William "Conqueror" I of England
Great x 2 Grandmother: Adelaide Burgundy Duchess Brabant 1233-1273 5 x Great Grand Daughter of King William "Conqueror" I of England
Great x 4 Grandfather: Robert Capet III Count Dreux 1185-1234
Great x 3 Grandmother: Yolande Capet Duchess Burgundy 1212-1248
Mother: Marie Évreux Duchess of Brabant 2 x Great Grand Daughter of King Henry III of England
Great x 4 Grandfather: Louis "Lion" VIII King France 3 x Great Grand Son of King William "Conqueror" I of England
Great x 3 Grandfather: Robert Capet Count of Artois Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandmother: Blanche Ivrea Queen Consort France Grand Daughter of King Henry "Curtmantle" II of England
Great x 2 Grandfather: Robert Artois II Count Artois 2 x Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Henry Reginar II Duke Brabant 1207-1248 3 x Great Grand Son of King William "Conqueror" I of England
Great x 3 Grandmother: Matilda Reginar Countess Saint Pol 1224-1288 4 x Great Grand Daughter of King William "Conqueror" I of England
Great x 1 Grandfather: Philip Artois 3 x Great Grand Son of King Henry "Curtmantle" II of England
Great x 4 Grandfather: Robert Seigneur Courtenay
Great x 3 Grandfather: Peter Courtenay
Great x 2 Grandmother: Amice Countenay Countess Artois -1275 4 x Great Grand Daughter of King Henry I "Beauclerc" England
Great x 4 Grandfather: Gaucher de Joigny
Great x 3 Grandmother: Peronnelle de Joigny 3 x Great Grand Daughter of King Henry I "Beauclerc" England
Great x 4 Grandmother: Amicie de Montfort 2 x Great Grand Daughter of King Henry I "Beauclerc" England
GrandMother: Margaret Artois Countess Évreux 1285-1311 Great Grand Daughter of King Henry III of England
Great x 4 Grandfather: Peter of Dreux aka Mauclerc Duke Brittany
Great x 3 Grandfather: John "The Red" Capet I Duke Brittany 4 x Great Grand Son of King Henry I "Beauclerc" England
Great x 4 Grandmother: Alix Thouars Duchess of Brittany 1201-1221 3 x Great Grand Daughter of King Henry I "Beauclerc" England
Great x 2 Grandfather: John Capet II Duke Brittany 5 x Great Grand Son of King William "Conqueror" I of England
Great x 4 Grandfather: Theobald IV King Navarre 3 x Great Grand Son of King William "Conqueror" I of England
Great x 3 Grandmother: Blanche "Navarre" Blois Duchess Brittany 4 x Great Grand Daughter of King William "Conqueror" I of England
Great x 1 Grandmother: Blanche Capet Grand Daughter of King Henry III of England
Great x 4 Grandfather: King John "Lackland" of England Son of King Henry "Curtmantle" II of England
Great x 3 Grandfather: King Henry III of England Son of King John "Lackland" of England
Great x 4 Grandmother: Isabella of Angoulême Queen Consort England
Great x 2 Grandmother: Beatrice Plantagenet Daughter of King Henry III of England
Great x 4 Grandfather: Raymond Berenguer Provence IV Count Provence 1198-1245
Great x 3 Grandmother: Eleanor of Provence Queen Consort England
Great x 4 Grandmother: Beatrice Savoy Countess Provence 1198-1267