I give my sister as a good example, her given name was Karolina, as a child she was known as one of the "babies" for she was the baby of the family. She started to object to that name when she was in grade school and we had to shift to calling her "Karrie". When a another sister had a child and called the Child "Carrie" we had a problem, who did we mean when we used the name "Carrie". "Karrie" reverted to her given name Karolina.
Notice I avoided the issue of "Mom" "Dad", "Papa" etc, which are names many people end up adopting for themselves when they have children. My father was known to various people as "Henry" "Hank". HAM" (The first letters of his first, middle and last names), depending on who he was talking to. Woman traditionally took their husband's last names upon marriage (a tradition driven by the fact that traditionally most women moved into the home of their husband's family NOT into a separate home, thus she become a person who lived in that family's house as opposed to the family she grew up in).
Thus even among males it is common to have more then one name, one name is often your profession. I have been called "Attorney" many a time, not as an attorney, but as my first name (and in some cases my only name).
If you look into other cultures, the you find people change names often. Among some Native American Tribes it was considered bad luck if your enemies found out your real name for they could then curse you, to prevent that members of those tribes used other names even within the tribe. You may be know by one nickname (lack of a better terms for these names) as an infant, as a pre teen by a another name, as a teen a third name, as an young adult a fourth name, as a parent a fifth name, and in your old age a sixth name. Each name reflected something in your life, something you did (Running bear, you ran like a bear), something that happened to you (Running Bear, for you ran as you where chased by a bear), Sitting bull, as an adult you decided it was better to sit then to stand but you acted like an old bull, old bear, old bull, old deer, as an senior in the tribe. Some of these names were related to an older nickname, some were not. Native Americans were also known to use different names when dealing with Whites then with people of their own tribe. A person may be known as "Stinking pond" for in the past he was caught in a stinking pond, but to outsiders he may be known as "Cougar who kills" for he was known to other tribes as a fierce warrior who fought like a cougar.
To a degree all people do what the Native Americans did, they name changed as circumstances changed. Your Grandmother may have known her neighbor as "Frank" but her family may have known her as "Mom" and later "Gramps". They may have known her given name was Francis, but never called her Frank, for when such a name was called for "Gramps" or "Mom" was better in their usage. I heard my father called many variation of the Name Henry, various people knew him by different versions of the name. At time this was disconcerting for even as Adults we called him simply "Dad". Thus the grandson NOT knowing that his Grandmother was sometimes called "Frank" does not surprise me, sometimes kids and grand-kids are the last to actually know the name they parents were known by other then "Dad" and "Mom" and later "Gramps". "Papa" and other variations of nicknames for Grandmother and Grandfather.
= new reply since forum marked as read