Smithsonian.com has a very interesting article about a Russian family that deliberately chose to turn its back on the rest of humanity.
A helicopter sent to find a safe spot to land a party of geologists was skimming the treeline a hundred or so miles from the Mongolian border when it dropped into the thickly wooded valley of an unnamed tributary of the Abakan, a seething ribbon of water rushing through dangerous terrain. The valley walls were narrow, with sides that were close to vertical in places, and the skinny pine and birch trees swaying in the rotors' downdraft were so thickly clustered that there was no chance of finding a spot to set the aircraft down. But, peering intently through his windscreen in search of a landing place, the pilot saw something that should not have been there. It was a clearing, 6,000 feet up a mountainside, wedged between the pine and larch and scored with what looked like long, dark furrows. The baffled helicopter crew made several passes before reluctantly concluding that this was evidence of human habitation—a garden that, from the size and shape of the clearing, must have been there for a long time.
It was an astounding discovery. The mountain was more than 150 miles from the nearest settlement, in a spot that had never been explored. The Soviet authorities had no records of anyone living in the district.
The four scientists sent into the district to prospect for iron ore were told about the pilots' sighting, and it perplexed and worried them. "It's less dangerous," the writer Vasily Peskov notes of this part of the taiga, "to run across a wild animal than a stranger," and rather than wait at their own temporary base, 10 miles away, the scientists decided to investigate. Led by a geologist named Galina Pismenskaya, they "chose a fine day and put gifts in our packs for our prospective friends"—though, just to be sure, she recalled, "I did check the pistol that hung at my side."
As the intruders scrambled up the mountain, heading for the spot pinpointed by their pilots, they began to come across signs of human activity: a rough path, a staff, a log laid across a stream, and finally a small shed filled with birch-bark containers of cut-up dried potatoes. Then, Pismenskaya said,
beside a stream there was a dwelling. Blackened by time and rain, the hut was piled up on all sides with taiga rubbish—bark, poles, planks. If it hadn't been for a window the size of my backpack pocket, it would have been hard to believe that people lived there. But they did, no doubt about it.... Our arrival had been noticed, as we could see.
The low door creaked, and the figure of a very old man emerged into the light of day, straight out of a fairy tale. Barefoot. Wearing a patched and repatched shirt made of sacking. He wore trousers of the same material, also in patches, and had an uncombed beard. His hair was disheveled. He looked frightened and was very attentive.... We had to say something, so I began: 'Greetings, grandfather! We've come to visit!'
The old man did not reply immediately.... Finally, we heard a soft, uncertain voice: 'Well, since you have traveled this far, you might as well come in.'
. . .
Slowly, over several visits, the full story of the family emerged. The old man's name was Karp Lykov, and he was an Old Believer—a member of a fundamentalist Russian Orthodox sect, worshiping in a style unchanged since the 17th century. Old Believers had been persecuted since the days of Peter the Great, and Lykov talked about it as though it had happened only yesterday; for him, Peter was a personal enemy and "the anti-Christ in human form"—a point he insisted had been amply proved by Tsar's campaign to modernize Russia by forcibly "chopping off the beards of Christians." But these centuries-old hatreds were conflated with more recent grievances; Karp was prone to complain in the same breath about a merchant who had refused to make a gift of 26 poods [940 pounds] of potatoes to the Old Believers sometime around 1900.
Things had only got worse for the Lykov family when the atheist Bolsheviks took power. Under the Soviets, isolated Old Believer communities that had fled to Siberia to escape persecution began to retreat ever further from civilization. During the purges of the 1930s, with Christianity itself under assault, a Communist patrol had shot Lykov's brother on the outskirts of their village while Lykov knelt working beside him. He had responded by scooping up his family and bolting into [the] forest.
That was in 1936, and there were only four Lykovs then—Karp; his wife, Akulina; a son named Savin, 9 years old, and Natalia, a daughter who was only 2. Taking their possessions and some seeds, they had retreated ever deeper into the taiga, building themselves a succession of crude dwelling places, until at last they had fetched up in this desolate spot. Two more children had been born in the wild—Dmitry in 1940 and Agafia in 1943—and neither of the youngest Lykov children had ever seen a human being who was not a member of their family. All that Agafia and Dmitry knew of the outside world they learned entirely from their parents' stories. The family's principal entertainment, the Russian journalist Vasily Peskov noted, "was for everyone to recount their dreams."
The Lykov children knew there were places called cities where humans lived crammed together in tall buildings. They had heard there were countries other than Russia. But such concepts were no more than abstractions to them. Their only reading matter was prayer books and an ancient family Bible. Akulina had used the gospels to teach her children to read and write, using sharpened birch sticks dipped into honeysuckle juice as pen and ink. When Agafia was shown a picture of a horse, she recognized it from her mother's Bible stories. "Look, papa," she exclaimed. "A steed!"
There's much more at the link. It's a fascinating - and strangely tragic - study of how isolation changes human behavior and interaction.