Is genealogy pointless?

[Vouthon]

What is the point in genealogy (ie researching your family history) beyond say, third great grandparents, when you might not even have inherited any DNA from these people? :sarcastic

An example from this article:

http://gcbias.org/2013/11/04/how-muc...ular-ancestor/

How much of your genetic material do you inherit from a particular ancestor? You inherit your mitochondria through your matrilineal lineage (your mum, your mum’s mum, your mum’s mum’s mum and so one) and your Y chromosome from your patrilineal lineage, but how is the rest of your genome spread across your ancestors in any given generation?

A generation ago you have two ancestors, your parents, two generations ago you have four grandparents (ignoring the possibility of inbreeding).
Each generation we go back your number of ancestors doubles, such that your number of ancestors k generations back grows at 2^k (again ignoring the possibility of inbreeding, which is a fair assumption for small k and if your ancestry derived from a large population).

However, you only have two copies of your autosomal genome, one from your mum one from your dad. Each generation we go back halves the amount of autosomal genome you receive, on average, from a particular ancestor. For example, on average 50% of your autosomal genome passed on from your mother comes from your maternal grandmother, 50% comes from your maternal grandfather. This material is inherited in large chunks, as chromosome fragments are inherited in large blocks between recombination events.

As you inherit autosomal material in large chunks there is some some spread around the amount of genetic material you receive; e.g. you might have inherited 45% of your autosomal material from your maternal grandmother, and 55% from your maternal grandfather. In my last post on this topic I looked at distribution of how much of your autosomes from grandparents, and I talked about why it was vanishingly unlikely that you received 0% of your genome from a grandparent.

We can take this back further, and look at the spread of how much of your autosomes you receive from ancestors further back, and how far we have to go back until it is quite likely that a particular ancestor contributed no genetic material on your autosomes to you. To do this I again made use of transmission data I had to hand to calculate these quantities using real data. Using data I had for one generation of transmissions, I compounded these together over multiple generations. After doing this I calculated a number of different quantities that I’ll describe below.

First lets look at the distribution of the number of autosomal genomic blocks you receive from a specific ancestor k generations ago

See this part too:

As a rough rule of thumb the autosomes you received from (say) your mother, k generations back is broken into (22+33*(k-1)) chucks, as your genome comes in 22 chromosomes and there are on average 33 recombination events per transmitted genome. These chunks are spread across your 2^(k-1) maternal ancestors. So, for example, nine generations ago the autosomes you receive from (say) your mum are broke, on average, into 286 large chunks, and these are spread across your 256 ancestors. Thus on average each of ancestors has contributed only a single block to you, and by chance it is possibly that they contribute zero. This gets worse the further we go back in time, your genome is broken up into more and more chunks, but this does not grow as fast as your number of ancestors. This makes it increasingly likely that you inherit no autosomal material from a particular ancestor.

All of these websites, TV shows (Who do you Think You Are? Finding Your Roots etc.)...are they all for nothing?

 

[Revoltingest]

Genealogy is interesting, but not so much so that I put any effort into it.
Others in the family have done research, & I bother to read only the highlights.
It's a connection, albeit tenuous, to history.

 

[Tarheeler]

I wouldn't say they're for nothing; different people are looking for different things in their genealogy. I have a few cousins that are big into it, and I help every now and then. We'll never get anything tangible out of it, but it's interesting to the histories of those who came before you unfold.

If a person finds value in that, then it isn't pointless.

 

[Vouthon]

Genealogy is interesting, but not so much so that I put any effort into it.
Others in the family have done research, & I bother to read only the highlights.
It's a connection, albeit tenuous, to history.

I agree that it can be interesting to get a personal connection with history. Everyone of our ancestors had to exist and reproduce for us to exist. This is fact.

However the further back we go in the tree, then the higher the probability that we actually have inherited no DNA from our ancestors. Sometimes I am fascinated by genealogy (I have traced mine myself back to the 1700s on some lines), yet at other times I just think it is a waste of time since I may not even have any genes from these people. I am conflicted about it.

 

[Revoltingest]

If the percentage of DNA really matters to someone, then that would be a problem.
My kids have none of my or Mrs Revolt's DNA, but they still have a sense of family.

 

[Vouthon]

If the percentage of DNA really matters to someone, then that would be a problem.
My kids have none of my or Mrs Revolt's DNA, but they still have a sense of family.

Yes but I am assuming that you raised your kids, which makes them your children

My great grandfather was not genetically my great grandfather but he was my great grandfather because I grew up with him (my biological gg died in WWII).

I'm speaking more of very distant people, such as our 5x great grandparents who lived in 1810 or 1780. What else connects us to these people, whom we could never have known in life or who our grandparents could not even have known, if not 'genes' or something else that still lives on in us?

 

[Revoltingest]

I don't see the genes as significant.
It's just about the familial connection.

 

[George-ananda]

Is genealogy a waste of time?

I find it interesting and fascinating, so to me it's not a waste. I love hearing the details of history even if they have no practical value.

For genetic stuff anything beyond the first couple levels is probably too watered down to be of much importance.

 

[Vouthon]

I don't see the genes as significant.
It's just about the familial connection.

Thanks Revolt. Perhaps I should be thinking of it in that sense then as well Its just when hundreds of years are involved (not 50 or even just 100), does it not strain even familial connections?

I mean people say they are descended from Charlemagne...but he lived over a thousand years ago and tens of millions must be descended from him. Indeed some speculate that all Europeans are descended from him (which I suppose shows how we are all one big family!). Is this really still 'family' history with a 'personal' connection to it?

 

[Vouthon]

Is genealogy a waste of time?

I find it interesting and fascinating, so to me it's not a waste. I love hearing the details of history even if they have no practical value.

For genetic stuff anything beyond the first couple levels is probably too watered down to be of much importance.

Good point.

One of the main uses of genealogy, I think, is its highlighting of social history. Individuals such as ordinary farming folk in the early 1800s in Yorkshire who might not find themselves remembered in official histories of famous people can have a paper trail waiting to be found to illuminate their lives.

 

[Revoltingest]

Thanks Revolt. Perhaps I should be thinking of it in that sense then as well Its just when hundreds of years are involved (not 50 or even just 100), does it not strain even familial connections?

I mean people say they are descended from Charlemagne...but he lived over a thousand years ago and tens of millions must be descended from him. Indeed some speculate that all Europeans are descended from him (which I suppose shows how we are all one big family!). Is this really still 'family' history with a 'personal' connection to it?

I take great pride in being descended from the very first proto-human.
I call him "Bob". I don't know his mate's name though.

 

[Windwalker]

I'm speaking more of very distant people, such as our 5x great grandparents who lived in 1810 or 1780. What else connects us to these people, whom we could never have known in life or who our grandparents could not even have known, if not 'genes' or something else that still lives on in us?

Doing genealogical research into my family has been a fascinating and rewarding exercise. It brings family together, connects us with the past, reaches out across time, teaches us about ourselves and the history of the past in where these people lived. It's brought me into contact with many relatives with whom we share our knowledge and information with each other, and many have become friends we have contact with regularly now. It brings a cohesiveness to family that tends to get lost in our modern life where we move away from one another an all live independently.

I began my research knowing of only 14 people who were relatives. My family tree now has over 2000 people in it, and I'm in contact with dozens of living relatives as a result. There is something about knowing ones own past, no matter how distant that is, that grounds us to our own selves.

And BTW, as far as genetic information, the grandson of one of my cousins I've come to know looks identical to my son, even though the two of them are 5th cousins.

 

[9-10ths_Penguin]

Genealogy is at least as useful as some of my hobbies (e.g. basket making and waving flags at race cars).

 

[Brinne]

I find it interesting.

Plus, since I'm related to Matthew Perry, whenever I go over to Japan I get a lot of "Wow Sugoi!" and bowing. In reality, I have pretty much zero of his DNA but hey it makes trips more interesting and certainly surprised my host family over there.

 

[Vouthon]

I think this website explains it well:

Q&A: Everyone Has Two Family Trees – A Genealogical Tree and a Genetic Tree - The Genetic Genealogist

DNA is randomly passed down from generation to generation. A parent does not pass on their entire genetic makeup to a child; as a result, bits and pieces of DNA are lost in each generation...

Two Family Trees

In reality, everyone has two family trees. The first is a Genealogical Tree, which is every ancestor in history that had a child who had a child who had a child that ultimately led to you. Every decision made by every person in that tree contributed to who and what you are today. However, not every person in that tree contributed a segment of your DNA sequence (because of random inheritance, as discussed above)

. As a result, we have a second family tree - a Genetic Tree – which is a tree that contains only those ancestors who contributed to our DNA. No one has yet been able to construct their Genetic Tree, but soon it will be a reality thanks to advances in genetic sequencing and comparison such Relative Finder. These tools are using relatedness between people living today to deduce the inheritance of DNA from people who have been dead for centuries.

I have many questions about Genetic Trees that I’m looking forward to answering with new tools in the future, including the following:
•At 10 generations, I have approximately 1024 ancestors (although I know there is some overlap). How many of these ancestors are part of my Genetic Tree? Is it a very small number? A surprisingly large number?
•What percentage, on average, of an individual’s genealogical tree at X generations is part of their genetic tree?

We all have two Family Trees: our "biological tree" and our "genetic tree".

To be honest, I think I was overemphasising DNA. If my mother's father's mother's father's mother's mother's father's mother doesn't share my DNA, she is still my ancestor and if she didn't exist nor would I :flirt:

 

[Ralphg]

For 'long-term' ancestry you should look at the lines on someone's hands. The more they make a match, the closer you are to each other on a real long evolutionary scale. You can also compare each other's nose to get an idea, comparing noses is also a way to get an idea from which ape-kind you originate.

I am an orphan so I don't know anything about my direct family but I know they originate from 'a long time ago'...
Made this pic for you so you can see for yourself (I dare you to find anyone with a hand like that ):
[GALLERY=media, 8382]ANKH_sign by Ralphg posted Oct 26, 2017 at 1:05 PM[/GALLERY]