Over the holiday season I spent a bit of time messing about with family history research.
One of the things I found was that if your ancestors got up in the morning, went to work, didn't end up in court, or burn down public buildings, they don't leave much of a trace in public documentation sources like newspaper archives.
Just the same as they don't end up in military records, or indeed convict records. but if they come from a country with a functioning public records system, you can at least trace the shape of their lives back to the 1850's, and possibly earlier, that is providing no one burned down the records office or pulped the records as no longer required.
The other sort of thing one can have are collections of letters passed down. This is particularly so in countries built on the back of migrant communities such as Australia, where people's ancestors may have come from places without a public records system, or one where war, revolution, and ordinary disasters has introduced gaps into the system.
However, even though the records may have gone a lot of places had an excellent postal system, which means that if you have the shoebox of granny's letters when she was still a schoolgirl in the Ukraine, you can trace your missing ancestors - maybe.
Certainly you can trace the aunts an uncles from the contents and perhaps a little more from old love letters, but you still come up against the problem that paper burns.
But if you could trace the DNA, maybe you might get a match from the stamp, or the envelope - sealed with a loving kiss - which I guess might well be driving the move to offer DNA testing of old letters - and that might offer people closure of some sort, particularly if your family was torn apart by the chaos that engulfed places like the Ukraine in the early part of the twentieth century.
There are of course other scenarios, Indian sailors who jumped ship and went to work in a curry house is one that comes to mind, or indeed trace the movements of British soldiers around the empire, and indeed the wives and sweethearts (and perhaps children) they left behind ...