On 04 Aug 1632 [his father] Charles Seymour 2nd Baron Seymour Trowbridge (age 11) and Mary Smith (age 11) were married. They had one son and two daughters He a great x 4 grandson of King Henry VII of England and Ireland. 
In 1654 [his father] Charles Seymour 2nd Baron Seymour Trowbridge (age 33) and [his mother] Eizabeth Alington 2nd Baroness Seymour Trowbridge (age 18) were married. She by marriage Baroness Seymour Trowbridge. They had five sons and two daughters. They were fourth cousins. He a great x 4 grandson of King Henry VII of England and Ireland.
On 17 Jan 1658 Francis Seymour 5th Duke Somerset was born to Charles Seymour 2nd Baron Seymour Trowbridge (age 37) and Eizabeth Alington 2nd Baroness Seymour Trowbridge (age 22).
On 12 Jul 1664 [his grandfather] Francis Seymour 1st Baron Seymour Trowbridge (age 74) died. He was buried in the Chanel of St Mary's Church, Great Bedwyn [Map]. His son [his father] Charles Seymour 2nd Baron Seymour Trowbridge (age 43) succeeded 2nd Baron Seymour Trowbridge.
On 25 Aug 1665 [his father] Charles Seymour 2nd Baron Seymour Trowbridge (age 44) died, possibly of plague. His son Francis Seymour 5th Duke Somerset (age 7) succeeded 3rd Baron Seymour Trowbridge.
On 29 Apr 1675 John Seymour 4th Duke Somerset 1645-1675 (age 30) died. He was buried at Salisbury Cathedral [Map]. His first cousin once removed Francis Seymour 5th Duke Somerset (age 17) succeeded 5th Duke Somerset, 5th Earl Hertford. Marquess Hertford extinct.
On 20 Apr 1678 Francis Seymour 5th Duke Somerset (age 20) was killed. He was unmarried and childless. He was shot dead by Genoese Horatio Botti whose wife Seymour was said to have insulted at Lerici. His brother [his brother] Charles Seymour 6th Duke Somerset (age 15) succeeded 6th Duke Somerset, 6th Earl Hertford.
Paternal Family Tree: Seymour
Maternal Family Tree: Margaret Macwilliams Baroness Stanhope
Kings Wessex: Great x 19 Grand Son of King Edmund "Ironside" I of England
Kings Gwynedd: Great x 16 Grand Son of Owain "Great" King Gwynedd 1100-1170
Kings Seisyllwg: Great x 21 Grand Son of Hywel "Dda aka Good" King Seisyllwg King Deheubarth
Kings Powys: Great x 16 Grand Son of Maredudd ap Bleddyn King Powys 1047-1132
Kings England: Great x 5 Grand Son of King Henry VII of England and Ireland
Kings Scotland: Great x 15 Grand Son of William "Lion" I King Scotland
Kings Franks: Great x 15 Grand Son of Louis VII King Franks
Kings France: Great x 8 Grand Son of Charles "Beloved Mad" VI King France
Great x 4 Grandfather: John Seymour 9 x Great Grand Son of King John "Lackland" of England
Great x 3 Grandfather: Edward Seymour 1st Duke Somerset 6 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Margery Wentworth
5 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: Edward Seymour 1st Earl Hertford 5 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Edward Stanhope
Great x 3 Grandmother: Anne Stanhope Duchess Somerset 4 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Elizabeth Bourchier
3 x Great Grand Daughter of King Edward III of England
Great x 1 Grandfather: Edward Seymour 2 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Thomas Grey 2nd Marquess Dorset
4 x Great Grand Son of King Edward III of England
Great x 3 Grandfather: Henry Grey 1st Duke of Suffolk 5 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Margaret Wotton Marchioness Dorset
Great x 2 Grandmother: Catherine Grey Countess Hertford Great Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandfather: Charles Brandon 1st Duke of Suffolk 6 x Great Grand Son of King Edward "Longshanks" I of England
Great x 3 Grandmother: Frances Brandon Duchess of Suffolk
Grand Daughter of King Henry VII of England and Ireland
Great x 4 Grandmother: Mary Tudor Queen Consort France
Daughter of King Henry VII of England and Ireland
GrandFather: Francis Seymour 1st Baron Seymour Trowbridge 3 x Great Grand Son of King Henry VII of England and Ireland
Great x 1 Grandmother: Honora Rogers
Father: Charles Seymour 2nd Baron Seymour Trowbridge 4 x Great Grand Son of King Henry VII of England and Ireland
Great x 1 Grandfather: Gilbert Prynne of Allington
GrandMother: Frances Prynne 7 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Thomas Carey
5 x Great Grand Son of King Edward "Longshanks" I of England
Great x 3 Grandfather: John Carey 4 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Margaret Spencer 3 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: Wymond Carey 5 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Edmund Denny
Great x 3 Grandmother: Joyce Denny 7 x Great Grand Daughter of King Edward "Longshanks" I of England
Great x 4 Grandmother: Mary Troutbeck 6 x Great Grand Daughter of King Edward "Longshanks" I of England
Great x 1 Grandmother: Jane Davys 6 x Great Grand Daughter of King Edward III of England
Francis Seymour 5th Duke Somerset 1658-1678 5 x Great Grand Son of King Henry VII of England and Ireland
Great x 4 Grandfather: Giles Alington
Great x 3 Grandfather: Robert Alington 9 x Great Grand Son of King Edward "Longshanks" I of England
Great x 4 Grandmother: Ursula Drury 8 x Great Grand Daughter of King Edward "Longshanks" I of England
Great x 2 Grandfather: Giles Alington 10 x Great Grand Son of King Edward "Longshanks" I of England
Great x 1 Grandfather: Giles Alington 11 x Great Grand Son of King Edward "Longshanks" I of England
GrandFather: William Alington 1st Baron Alington 12 x Great Grand Son of King Edward "Longshanks" I of England
Mother: Eizabeth Alington 2nd Baroness Seymour Trowbridge 8 x Great Grand Daughter of King Edward III of England
Great x 3 Grandfather: Lionel Tollemache
Great x 2 Grandfather: Lionel Tollemache 1st Baronet
Great x 4 Grandfather: Ambrose Jermyn
Great x 3 Grandmother: Susan Jermyn
Great x 4 Grandmother: Anne Heveningham
Great x 1 Grandfather: Lionel Tollemache 2nd Baronet 8 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Gregory Cromwell 1st Baron Cromwell Oakham
14 x Great Grand Son of King Henry I "Beauclerc" England
Great x 3 Grandfather: Henry Cromwell 2nd Baron Cromwell Oakham 7 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Elizabeth Seymour Baroness Cromwell Oakham 6 x Great Grand Daughter of King Edward III of England
Great x 2 Grandmother: Katherine Cromwell 7 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: John Paulet 2nd Marquess Winchester
8 x Great Grand Son of King Henry III of England
Great x 3 Grandmother: Mary Paulett Baroness Cromwell Oakham 6 x Great Grand Daughter of King Edward III of England
Great x 4 Grandmother: Elizabeth Willoughby
5 x Great Grand Daughter of King Edward III of England
GrandMother: Elizabeth Tollemache Baroness Alington 7 x Great Grand Daughter of King Edward III of England
Great x 4 Grandfather: Edward Stanhope
Great x 3 Grandfather: Michael Stanhope 4 x Great Grand Son of King Edward III of England
Great x 4 Grandmother: Elizabeth Bourchier 3 x Great Grand Daughter of King Edward III of England
Great x 2 Grandfather: John Stanhope 1st Baron Stanhope 5 x Great Grand Son of King Edward III of England
Great x 4 Grandfather: Nicholas Rawson of Aveley in Essex
Great x 3 Grandmother: Anne Rawson
Great x 4 Grandmother: Beatrix Cooke
Great x 1 Grandmother: Elizabeth Stanhope Lady Talmash 6 x Great Grand Daughter of King Edward III of England
Great x 3 Grandfather: Henry Macwilliams
Great x 2 Grandmother: Margaret Macwilliams Baroness Stanhope