Nielsen Hayden genealogy
Family: Llywelyn ap Seisyll, King of Deheubarth / Angharad ferch Maredudd (F3363)
m. 994-
Father | Male
Llywelyn ap Seisyll, King of Deheubarth
Born Abt 980 Died 1023 Buried Married 994 [1] Father Seisyll | F5959 Group Sheet Mother Prawst | F5959 Group Sheet
Mother | Female
Angharad ferch Maredudd
Born Died Buried Other Spouse Cynfyn ap Gwerystan | F2994 Married Father Maredudd ap Owain | F727 Group Sheet Mother
Child 1 | Male
+ Gruffydd ap Llywelyn, King of Wales
Born Died 5 Aug 1064 Ireland 
Buried Spouse Ealdgyth of Mercia, Queen Consort of England | F4951 Married Abt 1057
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Sources - [S145] Ancestral Roots of Certain American Colonists Who Came to America Before 1700 by Frederick Lewis Weis and Walter Lee Sheppard, Jr. 8th edition, William R. Beall & Kaleen E. Beall, eds. Baltimore: Genealogical Publishing Company, 2004, 2006, 2008.
- [S145] Ancestral Roots of Certain American Colonists Who Came to America Before 1700 by Frederick Lewis Weis and Walter Lee Sheppard, Jr. 8th edition, William R. Beall & Kaleen E. Beall, eds. Baltimore: Genealogical Publishing Company, 2004, 2006, 2008.