This was the custom or pattern of most European families
While today's parents may feel free to chose children's names without regard for an unwritten rule, the Irish traditions of selecting children's names may actually prove a good tool for anyone trying to research Irish family history. Children within a family were traditionally named according to the following pattern:
First son after father's father
Second son after mother's father
Third son after father
Fourth son after father's oldest brother
Fifth son after mother's oldest brother
First daughter after mother's mother (or father's mother)
Second daughter after father's mother (or mother's mother)
Third daughter after mother
Fourth daughter after mother's oldest sister
Fifth daughter after father's oldest sister
It's important to consider names in all their forms when looking at family use of the traditional naming patterns. A few examples are:
Don't know about that .. All I know is that in my mother's family everyone is named Bill .. Mary ... Elizabeth .. Mary Elizabeth .. Anne .. Bill .. Margret .. Margret Mary .. did I mention Bill .. that was a VERY common name .. there were so many Bill's I lost count .. LOL