For those who are interested, it should be noted that the traditional Welsh way of naming children resembles the Arabic way of naming them. That means to say, the use one of two small words to indicate ‘son of’: bin and ibn in Arabic. (In North Africa, bin changes to ben.)
Patronymic names— names based on the father’s name—work this way in the two langiages: Muhammad the son of Sultan would be Muhammad bin Sultan. A girl called Farida who is the daughter of Muhammad would be called Farida bint Muhammad.
In Welsh, Iwan (John) the son of Rhys would be Iwan ap Rhys. But if his father’s name was Owain, his name would be Iwan ab Owain. The sound and ease of saying the two words largely determines where it is ap or ab before the name.
In traditional Welsh, a girl would be named in the following way: Eira daughter of Iwan would be Eira ferch Iwan, where ferch, the mutated form of merch (daughter), indicates the relationship.
I find it very interesting that Wales and the Arab world shared a similar naming system.
NB: In these two excellent videos on Wales and Welsh names, whilst the information is correct, the pronunciation of the names is often lamentable! 😢 — © Mark Alexander