On 17 Jan 1884 [his father] Gerald Fitzgerald 5th Duke Leinster 1851-1893 (age 32) and [his mother] Hermione Wilhelmina Duncombe Duchess Leinster 1864-1895 (age 19) were married. She the daughter of William Duncombe 1st Earl Feversham (age 54) and Mabel Violet Graham Countess Feversham (age 50). He the son of Charles William Fitzgerald Fitzgerald 4th Duke Leinster 1819-1887 (age 64) and Caroline Leveson-Gower Duchess Leinster 1827-1887 (age 56). He a great x 5 grandson of King Charles II of England Scotland and Ireland. 
On 10 Feb 1887, coincidentally the same day his father died, 10 February, [his grandfather] Charles William Fitzgerald Fitzgerald 4th Duke Leinster 1819-1887 (age 67) died at Carton House, Carton, Kildare, County Kildare. His son [his father] Gerald Fitzgerald 5th Duke Leinster 1851-1893 (age 35) succeeded 5th Duke Leinster. [his mother] Hermione Wilhelmina Duncombe Duchess Leinster 1864-1895 (age 22) by marriage Duchess Leinster.
On 01 Mar 1887 Maurice Fitzgerald 6th Duke Leinster was born to Gerald Fitzgerald 5th Duke Leinster 1851-1893 (age 35) and Hermione Wilhelmina Duncombe Duchess Leinster 1864-1895 (age 22) at Kilkea Castle, Castledermot, County Kildare.
On 01 Dec 1893 [his father] Gerald Fitzgerald 5th Duke Leinster 1851-1893 (age 42) died of typhoid. His son Maurice Fitzgerald 6th Duke Leinster (age 6) succeeded 6th Duke Leinster.
On 19 Mar 1895 [his mother] Hermione Wilhelmina Duncombe Duchess Leinster 1864-1895 (age 30) died of tuberculosis at Menton.
On 04 Feb 1922 Maurice Fitzgerald 6th Duke Leinster (age 34) died having spent most of his life being cared for in a psychiatric institution at Edinburgh [Map]. His brother [his brother] Edward Fitzgerald 7th Duke Leinster 1892-1976 (age 29) succeeded 7th Duke Leinster.
Paternal Family Tree: Fitzgerald
Maternal Family Tree: Elizabeth Helena MacDonnell 1747-1796
Descendants Family Trees:
Kings Wessex: Great x 23 Grand Son of King Edmund "Ironside" I of England
Kings Gwynedd: Great x 20 Grand Son of Owain "Great" King Gwynedd 1100-1170
Kings Seisyllwg: Great x 24 Grand Son of Hywel "Dda aka Good" King Seisyllwg King Deheubarth
Kings Powys: Great x 21 Grand Son of Maredudd ap Bleddyn King Powys 1047-1132
Kings England: Great x 6 Grand Son of King Charles II of England Scotland and Ireland
Kings Scotland: Great x 18 Grand Son of Robert "The Bruce" I King Scotland
Kings Franks: Great x 20 Grand Son of Louis VII King Franks
Kings France: Great x 8 Grand Son of Henry IV King France
Great x 4 Grandfather: Robert Fitzgerald 19th Earl of Kildare 1675-1743 8 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: James Fitzgerald 1st Duke Leinster 1722-1773 9 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Mary O'Brien Countess Kildare -1730 11 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: William Robert Fitzgerald 2nd Duke Leinster 1749-1804 2 x Great Grand Son of King Charles II of England Scotland and Ireland
Great x 4 Grandfather: Charles Lennox 2nd Duke Richmond
Grand Son of King Charles II of England Scotland and Ireland
Great x 3 Grandmother: Emilia Mary Lennox Duchess Leinster 1731-1814 Great Grand Daughter of King Charles II of England Scotland and Ireland
Great x 4 Grandmother: Sarah Cadogan Duchess Richmond 1705-1751
Great x 1 Grandfather: Augustus Fitzgerald 3rd Duke Leinster 1791-1874 3 x Great Grand Son of King Charles II of England Scotland and Ireland
GrandFather: Charles William Fitzgerald Fitzgerald 4th Duke Leinster 1819-1887 4 x Great Grand Son of King Charles II of England Scotland and Ireland
Great x 4 Grandfather: William Stanhope 1st Earl of Harrington 1683-1756
9 x Great Grand Son of Henry IV King England
Great x 3 Grandfather: William Stanhope 2nd Earl of Harrington 1719-1779 10 x Great Grand Son of Henry IV King England
Great x 2 Grandfather: Charles Stanhope 3rd Earl of Harrington 1753-1829 2 x Great Grand Son of King Charles II of England Scotland and Ireland
Great x 4 Grandfather: Charles Fitzroy 2nd Duke Grafton
Grand Son of King Charles II of England Scotland and Ireland
Great x 3 Grandmother: Caroline Fitzroy Countess Harrington Great Grand Daughter of King Charles II of England Scotland and Ireland
Great x 4 Grandmother: Henrietta Somerset Duchess Grafton 1690-1726
11 x Great Grand Daughter of King Edward III of England
Great x 1 Grandmother: Charlotte Augusta Stanhope Duchess Leinster 1793-1859 3 x Great Grand Daughter of King Charles II of England Scotland and Ireland
Great x 3 Grandfather: John Fleming 1st Baronet
Great x 2 Grandmother: Jane Fleming Countess Harrington
Father: Gerald Fitzgerald 5th Duke Leinster 1851-1893 5 x Great Grand Son of King Charles II of England Scotland and Ireland
Great x 4 Grandfather: John Leveson-Gower 1st Earl Gower 10 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Granville Leveson-Gower 1st Marquess Stafford 10 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Evelyn Pierrepont Baroness Gower
9 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: George Granville Leveson-Gower 1st Duke Sutherland 8 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Scroop Egerton 1st Duke Bridgewater
6 x Great Grand Son of King Henry VII of England and Ireland
Great x 3 Grandmother: Louisa Egerton Countess Gower 1723-1761 7 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandmother: Rachel Russell Duchess Bridgewater
10 x Great Grand Daughter of Henry IV King England
Great x 1 Grandfather: George Sutherland Leveson-Gower 2nd Duke Sutherland 9 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: William Sutherland 17th Earl Sutherland 1708-1750 8 x Great Grand Son of King Henry VII of England and Ireland
Great x 3 Grandfather: William Sutherland 18th Earl Sutherland 1735-1766 8 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandmother: Elizabeth Wemyss Countess Sutherland 7 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 2 Grandmother: Elizabeth Sutherland Duchess Sutherland 19th Countess Sutherland 9 x Great Grand Daughter of King Henry VII of England and Ireland
GrandMother: Caroline Leveson-Gower Duchess Leinster 1827-1887 10 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Henry Howard 4th Earl Carlisle
10 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Frederick Howard 5th Earl Carlisle 11 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Isabella Byron Countess Carlisle 1721-1795
12 x Great Grand Daughter of King Edward "Longshanks" I of England
Great x 2 Grandfather: George Howard 6th Earl Carlisle 1773-1848 9 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Granville Leveson-Gower 1st Marquess Stafford 10 x Great Grand Son of King Edward III of England
Great x 3 Grandmother: Margaret Caroline Leveson-Gower Countess Carlisle -1824 8 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandmother: Louisa Egerton Countess Gower 1723-1761 7 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 1 Grandmother: Harriet Elizabeth Georgiana Howard Duchess Sutherland 10 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: William Cavendish 4th Duke Devonshire
11 x Great Grand Son of Henry IV King England
Great x 3 Grandfather: William Cavendish 5th Duke Devonshire 8 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandmother: Charlotte Elizabeth Boyle Marchioness Hartington
7 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 2 Grandmother: Georgiana Cavendish Countess Carlisle 1783-1858 9 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: John Spencer 1st Earl Spencer
9 x Great Grand Son of King Henry VII of England and Ireland
Great x 3 Grandmother: Georgiana Spencer Duchess Devonshire 10 x Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandmother: Margaret Georgiana Poyntz Countess Spencer
11 x Great Grand Daughter of King Edward III of England
Maurice Fitzgerald 6th Duke Leinster 1887-1922 6 x Great Grand Son of King Charles II of England Scotland and Ireland
Great x 4 Grandfather: Thomas Duncombe
Great x 3 Grandfather: Charles Slingsby Duncombe 11 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Sarah Slingsby 10 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: Charles Duncombe 1st Baron Feversham 12 x Great Grand Son of King Edward III of England
Great x 1 Grandfather: William Duncombe 2nd Baron Feversham 13 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: George Legge
12 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: William Legge 2nd Earl Dartmouth 13 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Elizabeth Kaye Baroness North and Guildford
Great x 2 Grandmother: Charlotte Legge Baroness Feversham Duncombe Park 14 x Great Grand Daughter of King Edward III of England
GrandFather: William Duncombe 1st Earl Feversham 14 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Alexander Stewart 6th Earl Galloway
11 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: John Stewart 7th Earl Galloway 1736-1806 12 x Great Grand Son of King Edward III of England
Great x 2 Grandfather: George Stewart 8th Earl Galloway 1768-1834 13 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: James Dashwood 2nd Baronet
Great x 3 Grandmother: Anne Dashwood Countess Galloway 1743-1830
Great x 4 Grandmother: Elizabeth Spencer Lady Dashwood
Great x 1 Grandmother: Louisa Stewart Baroness Feversham Duncombe Park 14 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Nicholas Bayly 2nd Baronet Bayly of Plas Newydd in Anglesey
Great x 3 Grandfather: Henry Bayly-Paget 1st Earl Uxbridge 12 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Caroline Paget Lady Plas Newydd Anglesey
11 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Jane Paget Countess Galloway 1774-1842 13 x Great Grand Daughter of King Edward III of England
Mother: Hermione Wilhelmina Duncombe Duchess Leinster 1864-1895 15 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Very Reverend William Graham
Great x 3 Grandfather: Reverend Robert Graham
Great x 4 Grandmother: Mary Offley
Great x 2 Grandfather: James Graham 1st Baronet
Great x 1 Grandfather: James Graham 2nd Baronet 14 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Alexander Stewart 6th Earl Galloway 11 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: John Stewart 7th Earl Galloway 1736-1806 12 x Great Grand Son of King Edward III of England
Great x 2 Grandmother: Catherine Stewart Lady Graham 13 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: James Dashwood 2nd Baronet
Great x 3 Grandmother: Anne Dashwood Countess Galloway 1743-1830
Great x 4 Grandmother: Elizabeth Spencer Lady Dashwood
GrandMother: Mabel Violet Graham Countess Feversham 15 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: Colonel James Campbell of Ardkinglass
Great x 1 Grandmother: Frances "Fanny" Callander Lady Graham 20 x Great Grand Daughter of King John "Lackland" of England
Great x 3 Grandfather: 18 x Great Grand Son of King John "Lackland" of England
Great x 4 Grandmother: Rachel Skeffington Countess Antrim
17 x Great Grand Daughter of King John "Lackland" of England
Great x 2 Grandmother: Elizabeth Helena MacDonnell 19 x Great Grand Daughter of King John "Lackland" of England