Onomastics or cultural naming conventions can yield genealogical clues that may lead you to previous generations.
My first examples come from David Hackett Fischer’s Albion’s Seed, which is a long, dense but surprisingly accessible book on Colonial American cultural traditions.
The most useful naming convention from a genealogically perspective is the colonial Virginian custom of using a mother’s maiden name as a forename for sons—for example, the son of Joseph Chew and Ruth Larkin was named Larkin Chew. Anytime you see an odd forename in Virginia, look for people from the same place with that odd forename as a surname, and you may very well get closer to the maternal line.
Virginians also typically named their first-born son after their paternal grandfather, and the second-born son after the father. In some families, you’ll see that pattern repeated for generations.
Scotch-Irish tended to follow the same pattern, naming the first-born son after the paternal grandfather, and the second- or third-born son after the father. The preferred different names than Virginians, but the pattern was the same.
Quakers followed the pattern of “honoring the mother’s father and the father’s mother” by naming the first-born daughter and son after those individuals. While it wasn’t a 100% thing, if you know you’re looking at the eldest son and have a maiden name for the mother, you probably know the maternal grandfather’s name.
New England Puritans don’t have as helpful patterns, however. They often named the first-born son after his father, and the first-born daughter after her mother. If you’ve figure out birth order, you’ve probably already worked out who the parents were.
Puritans embraced necronyms or naming a newborn after a deceased sibling. Fischer notes that 80% of the time a child died, the next child born of the same sex was given the name of the deceased child. That won’t help you break through brick walls, but it will help you avoid the mistake of thinking you have two families with identically named kids born in different years.
Puritans also had the singular practice of closing their eyes, pointing to a page in the bible, and naming their child after that word. That’s why you’ll see names such as Thankful, Wrestling and Notwithstanding. The best of these is Fly’s Fornication. Poor woman.
Moving to the Catholic tradition, there are two important naming conventions. The first is that of naming a child based on the Saint’s day the child was baptized or born on. This generally isn’t very useful genealogically, as there are multiple calendars of Saint’s Days, and many of the saints had similar names.
The second is naming a child after a godparent, and this also applies to Lutherans and other sects that follow this tradition. The naming by itself isn’t particularly important, but the godparent is. Being a godparent was not a casual matter: that person was supposed to take an important role in the child’s life, especially their spiritual life, so godparents were almost always close friends or family members. That means you should always take a close look at the sponsors on a baptismal record for potential family members.