Last February I did a short blog on this subject. Below is a more thorough version on how every 40 years or so I've observed a class of names once not as desirable become more so.
What do the names Deborah and Jordan have in common? What common experiences would a Kathleen born in the 19-aughts, a Joshua born in the 1940s, and a (male) Kelly born in the 1980s (like me) have?
This blog is about three classes of names that once had taboos in the United States, but are now (or are becoming) mainstream (in some cases again). They are (in chronological order of their grip on the name pool): Irish names, Biblical names, and unisex names for boys.
The first group that I'll discuss is Irish names. In the mid-19th century Ireland had a major potato famine, resulting in large numbers of Irish people moving to other lands in hope of having enough food. When the U.S. started having all these Irish people coming over, an "anti-Irish" sentiment crept in among a lot of other Americans. It got so bad that there were Irish people trying to hide their heritage (e.g. one of Nameberry's founders, Pamela Redmond Satran, had a grandmother Bridget who changed her name to Bertha). About 80 years or so after the mass Irish migration (aka a "saeculum" in terms of generational authors William Strauss and Neil Howe; their sites are at these links), the American population finally accepted the Irish and their names started to come back in vogue. As time went on, being Irish even became fashionable (e.g. St. Patrick's Day became a popular holiday, in 1960 we elected a President [Kennedy] of Irish decent who probably wouldn't have had a chance a generation earlier, and even non-Irish people became interested in using their names).
About 40 years or so (or if you prefer, half a saeculum) after the mass Irish immigration to America (and other places), another group started coming onto American shores in large numbers: Jews. Up until this point Biblical names had exhibited a fashion in America, but when the Jews (who were strong users of such names themselves) came along those names become passé to many Americans. Like the anti-Irish sentiment that was establised when they immigrated, an anti-Jewish one was formed as well. As with many Irish who tried to hide their roots, many Jews took steps themselves to do the same (resulting in names like Irving which do not have Hebrew origins themselves acquiring a "Jewish" connotation when used in large numbers by Jews). Although a few Biblical names remained in common use, such as Ruth in the early 20th century and Deborah in the mid-20th century as well as names like James and Elizabeth which no longer seemed "Biblical" to the masses despite their origins, this was the time when such names were generally unfashionable or even taboo. The renaissance for Biblical names, as with the rise of Irish names in America, came about in the 1970s or so (once again about 80 years after the tightening of the use of such names began) with names like Matthew and Rachel becoming mainstream. Today parents are going even more out with Biblical names with choices like Ezekiel and Ezra (which would've been downright eccentric a lifetime ago) on the rise.
Fast forward another half-saeculum from the time of large Jewish immigration and you have another event beginning to affect American naming trends. This time it's not a group immigrating in large numbers, but rather one of the events of the move to liberate women. Around the time the 20th century was a quarter over people started giving their daughters traditionally masculine names like Beverly and Shirley in large numbers. When these names started becoming popular on females in large numbers, people became afraid to bestow them on boys and some males who already had these names tried to "hide" them by going by a middle name or even changing their name. For the next 80 years or so there were many names that fell fate to this trend: Leslie, Kim, Jody, Shannon, Ashley, Madison, Taylor, and many others like these rose in popularity for girls but became passe for boys. Like Ruth and Deborah from the Biblical picks that hung on through the Jewish storm, a few like Casey and Jordan hung on through the unisex name on girls one. Now that a full saeculum has passed since boys-names-on-girls first became fashionable there are many people who are expressing interested in reviving these kinds of names for boys in spite of them also being used for girls. We're already seeing this with more "newer" unisex names like Hayden and Riley hanging on for both genders, recently fashionable androgynous picks like Morgan at worst falling in roughly the same proportions for both genders, and even a growing interest in reviving names like Kelly and Shannon for boys.
Back to my introduction statement for my blog: Deborah (in the 1950s) and Jordan (in the 1990s) share the fact that they both showed signs of the tide about to turn a generation or so before it did (the former with Biblical names and the latter with androgynous names for boys). The statement about these people born in these respective eras: Kathleen (in the 19-aughts), Joshua (in the 1940s), and Kelly (male, in the 1980s) demonstrate those who may have had a bit of a rough time with their name growing up, but by their adulthood the taboo on names like theirs began to be lifted and to younger generations their names would (or will likely) be considered ahead of the curve at worst.
If you're already familiar with the aforementioned Strauss & Howe cycle, you will notice that each of these "taboos" began around the start of an Awakening or Crisis era and ended a saeculum later around the start of the next era of the same type. Examples of Crisis eras are the Civil War era, the Great Depression/World War II era, and the current era (there is still debate over when the current Crisis era began; some say 9/11, some say when Hurricane Katrina struck, and some say when the economy fell in 2008). Examples of Awakening eras are the "Consciousness Revolution" of the 1960s and 70s, and before that the "Missionary Awakening" of the 1880s that lasted into the 19-aughts. Both the Irish and androgynous-boy taboos started around the beginning of a Crisis era and ended (or are ending) at the start of the next one, and the Biblical/Jewish taboo ran from the start of one Awakening to the next. If you get more into S&H's works you will learn that Awakenings are generally spiritual/religious in nature and Crises are generally secular in nature, which for the "name taboos" makes since since the one that ran from Awakening-Awakening was about a religious group (Jews) and the ones that ran from Crisis-Crisis were not (Irish, "feminine males").
After I initially prepared this blog, I thought what might be the current religion-based name taboo that would be due to break at the circa 2050 Awakening: Muslim/Arabic names. Right now in the years after 9/11 such names overall are less than desirable for many Americans, but by then the new Prophet generation may not think so.