I’d be interested in knowing where they got their info on slave families. I followed the link but it was just to a document that, not surprisingly, said that same thing but without cite.
As most people who don’t confuse John Wayne and John Wayne Gacey would know, it wasn’t at all uncommon at all for slave parents to live on separate plantations even while they were still together. Any slave children born were the property of whoever owned the mother- the father had no rights, and of course families were separated all the time.
There were absolutely no laws preventing husband and wife from being sold apart and their wedding vows often included the line “Till death or distance do us part”. While there were laws in some states preventing the separation of mother and child before the child was of a certain age (10 in some states, up to 14 in others) these were on par with the “you can’t bathe a mule in the bathtub” type laws as far as how stringently they were observed. Do the math: the only person likely to get majorly upset if the law was broken were the slave mother and her child[ren], and neither of them could legally bring charges, so it was 100%up to the discretion of the slave owner or his/her heirs. (Death of the owner was when families were very often separated.)
Not once in the the census were slaves listed by name or by family relationships, just strictly by number and age. In 1850 and 1860 Slave Schedules, which were more detailed by far than in previous censuses, the only name listed was the name of the owner; for the slaves themselves they recorded gender, age, and color (B for black, M for mulatto). If you had on the records that John Smith owns 10 slaves and they are
Male, 50, B
Female, 42, B
Female, 39, B
Male, 39, M
Female, 25, B
Male, 18, B
Female, 15, M
Female, 12, B
Male, 4, B
Male, 8/12, M {8/12 means 8 months}
There is absolutely no way of knowing what, if any, relationship they were to one another. The infant above might belong to any one of females 15 and above, and mulatto might mean it had a white father or mulatto parents. I’ve seen many many slave schedules, there’s no variation- and for really big plantations where there were hundreds of slaves, it’s even more obfuscated.
About the best you could possibly do if you really wanted a study of slave families would be to examine the private records of slaveowners who kept detailed records that survived to the present. Even then you’d only be able to make a statistical study of X number of plantations and it would be impossible to extrapolate it to encompass the whole slave population. One thing you learn when you study plantation records is that if you’ve seen one plantation you’ve seen one plantation: how they did things on Tara might be completely different from Twelve Oaks or Mimosa or Fair Oaks or whatever.
Longwinded response to a comment nobody made, but I hate people who talk out of their ass where history is concerned.