Cadoc was born around 497AD to Welsh parents. His father was Gwynllyw the Bearded who was a chief but thief and brother to St Petroc. His mother was Gwladys a daughter of King Brychan of Brycheiniog. Brychan refused their marriage but they eloped escaping from his court across the mountains when there was a raid. In the raid 200 of Gwynllyw's 300 men were killed.
So Cadoc was from two royal families and even before he was born it's said miracles started to happen, such as strange lights in his parent's home and food miraculously appearing in the cellar.
We know about Cadoc because there is a history written called Vita Cadoci which was written shortly before 1086 by Lifris of Llancarfan. Many astounding miracles are recorded within the life story.
The stories go that an angel announced Cadoc's birth and also summoned the hermit Meuthi to come baptise him and teach him. A holy well sprang up at the place of baptism which reportedly flowed with milk and wine. It's thought he was baptised at Cathmail (Cadfael). His father to celebrate the birth of his son went on a raid and stole the cow of an Irish monk called St Tathyw of Caerwent. This could be Tathan who was an abbot of Caerwent and whose dedications appear around Llantwit Major. Tathyw confronted Gwynllyw for the return of his cow. On impulse Gwynllyw offered Cadoc to go and train under Tathyw at his monastery in Caerwent. Here Cadoc learned Latin, had a basic education and was introduced to the life of a priest and monk. This all prepared him for his later time in Ireland.
One day Cadoc was trying to find a hiding place in a wood whilst he was being pursued by an enemy. An old boar appeared in front of him. The white haired animal tried to charge him three times but then miraculously disappeared. Cadoc marked the place with three branches. His Uncle King Pawl of Penychen owned the area and then gave it as a gift to Cadoc. The location became the site for the great monastery of Llancarfan. Cadoc founded it here but then went to Ireland to study for three years. He returned to Wales then went to Scotland where he founded another monastery at Cambuslang before returning again to Llancarfan. He greatly influenced the growth of this monastery.
He travelled to Brittany and settled in L'lle do Cado where he built an oratory and founded a monastery. There are many place names in this region dedicated to Cadoc.
It is not known whether he actually went to Cornwall, although from Wales to Brittany he probably did pass through the county, so it is certainly plausible that St Cadoc's chapel near Padstow was founded by him. The Saint's Way, the route pilgrims and sailors took overland to avoid the treacherous waters around Land's End started at Padstow and the chapel is just a few miles inland.