While it's rarely a challenge outside of old Spanish/Mexican genealogy, the idea of social caste strongly rears its "old school" head when dealing with the complexities of European (Spanish), mestizo, creole, mulatto, indio, and the numerous variations of how much percentage you are of one or another.
I was reminded of the challenge recently when contacted by a possible relative for more information. She had traced her ancestry to the second wife of my 3rd great grandfather, Nathaniel Pryor, who was born in Kentucky. When he came to California in 1827, Nathaniel was first suspected of being a spy for the Norte Americanos. After proving himself to the authorities for nine years, Nathaniel converted to Catholicism, learned Spanish, and was baptized with the Spanish name Miguel Luis.
The next year, "Miguel" married into the prominent land-owning Sepulveda family. In 1839, my 2nd great grandfather, Pablo Pryor, was born. His Sepulveda wife died the following year and "Miguel" waited another eight years before marrying again, this time to Maria Paula Romero. They had a son named Nathaniel in 1848 and two years later, "Miguel" Pryor died.
Pablo, my great great grandfather separated himself from his step-mother and brother when he was about 16.
My new "potential relation" contacted me seeking information about a Joaquina Pryor, whom she'd found through censuses, living with Maria Paula Pryor. She wondered if possibly, Joaquina was the daughter of "Miguel" or his son Pablo. Hmmm, I thought. Joaquina was supposed to have been born between 1855-1860, so "Miguel" was definitely not the father since he died in May of 1850.
Pablo Pryor didn't marry until 1864 and there's no record of him fathering any children until 1865. Not impossible for him to have fathered an illegitimate daughter, HOWEVER, she wouldn't have been sent to live with his estranged step-mother.
Also "Joaquina" doesn't show up until the 1870 census on which she is listed as "Joaquina Romero". A puzzlement. She's also listed as being 16 years of age (born in 1854?) and her father's birthplace is listed as "New York". I can believe a census taker messing up somehow (It happens!), but subsequent census records show the same father's birthplace. Weird!
Another problem brings me back to the caste challenge. The 1860 census records a Joaquina (no last name) as an indio (Native American) at the right age living near San Diego. In those times, it often happened that indio servants would take the surname of their employers. Also by 1870, a sort of political correctness crept into some census reports that made "indios" suddenly "white" unless they were still attached to reservations or Native American communities.
Of course, the Old Californio families ALL claimed to be strictly of Castillian Spanish heritage (that caste business again), and Joaquina was no exception. She and her descendants claimed to be of Spanish heritage through the Pryor "father".
Now, according to the records of those times (1700-1800s) NO ONE came directly to California from Spain. All the families, soldiers, etc. came up from Mexico, sometimes after a few years, sometimes after generations, sometimes after a few centuries, often after marrying mestizo, mulatto, or indio spouse. Today you may think none of this matters -- but then it mattered to those who wanted "pure Castillian roots".
Many mestizos and mulattos "bought" their way into "respectability" after a generation or two; many indios suddenly became pure Spanish by adopting the name of their patrons and employers. It becomes tricky to plot the genealogy!
The "problem" of Joaquina continues to challenge a resolve. Maybe someday, we'll know for sure who she really was, maybe not. It means a brick wall nonetheless for my "potential relative".