Nielsen Hayden genealogy
Descendants of Madog ap Gruffudd ab Owain Brogyntyn ap Madog
Abt 1200 -Mother: Jonet Say
Madog ap Gruffudd ab Owain Brogyntyn ap Madog (Abt 1200 - ??)
   └─ Iorwerth ap Madog ap Gruffudd ab Owain Brogyntyn
    Lleucu ferch Llywelyn ap Gruffudd
       └─ Madog ab Iorwerth ap Madog ap Gruffudd
        Efa ferch Llywelyn ap Gruffudd
           └─ Gwerfyl ferch Madog (of Hendwr in Edeirnion, Merionethshire, Wales - Aft 1293) =>
            + Gronwy ap Tydyr HĂȘn ap Gronwy (of Penmynydd, Anglesey, Wales - 1331 bur.Bangor, Gwynedd, Wales)