hi! other contributions are welcome (especially for regions other than Europe, China & Japan), but fyi, this sort of question comes occasionally in this sub, so you can get started on these previous posts
I'm not sure if this is too tangential or not, but I've done some work on Mormonism, and I think the answer might be relevant.
Mormons perform a ritual practice called Baptism for the Dead, in which a living person is baptised by proxy on behalf of someone who died without being baptised in the Mormon church. This comes up in the news periodically because of repeatedly baptising holocaust victims, Hitler etc. which upsets some communities. They keep on baptising Anne Frank, for example, having done so ten or so times.
Because of the controversy that has come up about this, the Mormon response was to declare in the 90s that they would only perform this ritual for people if their living relatives gave them permission, or if they could prove lineage.
This is what brought about familysearch.org, which is currently the largest genealogical database in the world, owned an operated by the church of latter day saints. The official byline is that connecting families across generations "brings joy and meaning to life", but instructions on getting a temple recommend to have a baptism for the dead performed appear on the second page of website's manual, so it's clearly a pretty important part of the whole process. At this point it's necessary to indicate that to get full access to the website you need a temple recommend from the Mormon church, which I do not have, so outside sources and ex-mormons are often the best sources.
In order to proceed with the objective of baptising every person who has ever lived, as well as complying with the edict of only baptising those who are relations, some enterprising mormons have traced their lineage all the way back to Adam and Eve.
Now, this is obviously a faith position, which most of us don't endorse. They also have a timeline of early figures based on biblical accounts, eg. early Christian figures like Noah living for hundreds of years. So, for some orthodox Mormons, they claim to trace their lineage back to the first man and woman. The story of how far back the accounts are actually accurate for those outside the tradition for would require a much more specialized knowledge than I have, as well as access to records that I do not have.
None the less, I think it's at very least interesting to know that the largest genealogical database is founded on religious interests.
For academic works on the subject, Akenson's Some Family or Davies's Mormon Culture of Salvation both have good accounts of baptism for the dead and their complex genealogical enterprise. For examples that are too casual to be examples here, you can check subreddits like /r/exmormon are full of accounts of people who engaged in the practice and talk about their experiences with genealogical research being considered devotional practice.
Hi!
I am an amateur genealogist with 5 years of experience. A lot of people have misconceptions about genealogy which I sometimes try to clear a bit.
Some people claim to have traced their lineage to biblical figures or various deities ( such as Norse Gods,...etc ). These people can simply be ignorant persons who have been mislead by what they read on the Internet or scammed. However, as it as been mentioned by dvb70 there are many examples of kings and such that supposedly descend from biblical figures, these often were political instruments to make their legitimacy to rule more ... legitimate.
Today, many people make their genealogy, or think they are doing so, in order to connect themselves to important persons such as royalty for example. I will not list you all the mistakes they do as it would be quite out of the subject. But give me two weeks and a few hundreds money and I can make you your family tree going back to Noah if you want with what would appear as proofs and sources ( though many forget about checking the facts they are given ). These are common scams today but they are as old as genealogy goes.
Know that everyone can research their lineage but how far they can get depends on plenty of elements and factors such as where do you live, where your family is from,...Etc The King of Belgium will certainly have an easier time finding his ancestors than me as they are more documented than my peasants and innkeepers forefathers.
You can research your lineage as long as records have been kept. In France for example, if you are good enough to do this kind of research many people will be able to find records up to the 1700s. A lot will find older records in the 1600s but there it starts to be harder to find and read of course. The dead end for very good researches in France is 1539 ( Bill of Villers-Côtterêts ). It's at this date that baptism records were mandatory in France. That does not mean you can't go further but it's very hard to find pertinant records on your " commoners " ancestors.
England and the UK are harder to make research as many archives were centralized in London and suffered the world wars. If you are American and your ancestors are black people it may be much harder to find your lineage than for someone descending from white people. If your ancestors were let say Christians living in the Ottoman Empire it will be very hard to find the basic baptism/marriage/death/burial records for the common people.
So indeed, it really depends on where your ancestors were from. Royalty and nobility generally have some of the best genealogy as they used to make their family tree for hundreds of years which is not the case for the common people. Even royalty's genealogy at some points can become " more suspicious " and subject to debate between historians.
I can't think of a proper genealogy that would show a royal family going back to the Antiquity as many people ask if it is possible ( but I may be wrong ). For examples, the Merovingians are said to descend from Merovech ( who gave his name to the dynasty ) but some historians seem to believe that he is a legendary figure ( creating even more confusions regarding Merovech's own ancestors ).
So that said, royalty and nobility can sometimes trace their family very far back. For others it depends on plenty of factors as I said but you can be lucky if you can research ( and prove! ) a branch of your family 400 years ago, sometimes more sometimes less. I would have a very hard time believing someone claiming to be a direct descendant of Julius Caesar or Jesus Christ or Thor.
Many Korean families have Family Lineage Books, called Jok-Bo, at every patriarch's house of the clan you're in. As a Kim whose clan is the Kimnyung Kims, (김녕 김씨), I can trace my lineage back to the 11th century. (according to the book- you have to remember that in the late 19th century towards the end of the Joseon Dynasty many freed slaves bought their way into the "lineage books" so it can't be trusted 100%, but it does have a good enough basis to trace one's lineage far back).
Similarly, I believe they have found descendants of Confucius in China, according to Wikipedia.
"Despite repeated dynastic change in China, the title of Duke Yansheng was bestowed upon successive generations of descendants until it was abolished by the Nationalist Government in 1935. The last holder of the title, Kung Te-cheng of the 77th generation, was appointed Sacrificial Official to Confucius. Kung Te-cheng died in October 2008, and his son, Kung Wei-yi, the 78th lineal descendant, had died in 1989. Kung Te-cheng's grandson, Kung Tsui-chang, the 79th lineal descendant, was born in 1975; his great-grandson, Kung Yu-jen, the 80th lineal descendant, was born in Taipei on January 1, 2006. Te-cheng's sister, Kong Demao, lives in mainland China and has written a book about her experiences growing up at the family estate in Qufu. Another sister, Kong Deqi, died as a young woman.[36]
Confucius's family, the Kongs, have the longest recorded extant pedigree in the world today. The father-to-son family tree, now in its 83rd generation,[37] has been recorded since the death of Confucius. According to the Confucius Genealogy Compilation Committee, he has 2 million known and registered descendants, and there are an estimated 3 million in all.[38] Of these, several tens of thousands live outside of China.[38] In the 14th century, a Kong descendant went to Korea, where an estimated 34,000 descendants of Confucius live today.[38] One of the main lineages fled from the Kong ancestral home in Qufu during the Chinese Civil War in the 1940s, and eventually settled in Taiwan.[36]"
As an aside, is it relevant to insist on a maternal line instead of a paternal one? I've read that illegitimacy runs anywhere from 3 to 10 percent per generation. Claiming ancestors on your father's side beyond a few hundred years would therefore be an issue of probability.
I guess if one looked at household vs. genetic offspring, then things would be different.
This may not be what you are looking for, but Cheddar Man, was shown to have 2 descendants living in the village near where he was found.
As a caveat, it seems 1 to 1.5% of Britain's population shares those markers.
*edit: Cheddar Man is 9000 years old.