Author Topic: Size of DNA data bases  (Read 987 times)

Offline sugarfizzle

  • RootsChat Veteran
  • *****
  • Posts: 619
    • View Profile
Re: Size of DNA data bases
« Reply #9 on: Tuesday 06 March 18 14:17 GMT (UK) »
Guy, I am not sure from your posts if you have had DNA testing and been disappointed with the results, or you have not had DNA testing.

Whether the former or the latter, I would think it is difficult for you to say with confidence that 'DNA testing is not really worth while for genealogy yet'.

It has been very worthwhile for me personally, another tool to help confirm ancestors.
No unexpected NPEs, which could easily happen with firstborn child from a couple.
Brick wall broken down for someone else, indicating something that I had thought highly likely from a paper trail, but nobody else was convinced.
Brick wall broken down for myself, ancestor with widely differing ages in census and age at death consistent with none of them.
Brick wall broken down for another ancestor of mine, indicating descent from family with different spelling of the name.

Caution may well be advised by yourself and others, for varying different reasons, but don't tell everyone that it isn't worth it for genealogy.  :)

Regards Margaret
STEER, mainly Surrey, Kent; PINNOCKS/HAINES, Gosport, Hants; BARKER, mainly Broadwater, Sussex; Gosport, Hampshire; LAVERSUCH, Micheldever, Hampshire; WESTALL, London, Reading, Berks; HYDE, Croydon, Surrey; BRIGDEN, Hadlow, Kent and London; TUTHILL/STEPHENS, London
WILKINSON, Leeds, Yorkshire and Liverpool; WILLIAMSON, Liverpool; BEARE, Yeovil, Somerset; ALLEN, Kent and London; GORST, Liverpool; HOYLE, mainly Leeds, Yorkshire

Census Information is Crown Copyright, from www.nationalarchives.go

RootsChat is the busiest, largest free family history forum site in the country. It is completely free to use. Register now.
Also register instantly with Facebook or Twitter (and other social networks). Start your genealogy search now.


Offline sugarfizzle

  • RootsChat Veteran
  • *****
  • Posts: 619
    • View Profile
Re: Size of DNA data bases
« Reply #10 on: Tuesday 06 March 18 14:24 GMT (UK) »
Thanks for your thoughts, Margaret, I am interested to explore a little more, please, some of the matters you mention.

Quote
The number at ancestry increases almost daily, the number at ftDNA only very slowly.
Have you paid to "unlock" your results and the tools at FTDNA? If not (which is the case with my cousin), then I think that is why you aren't getting many new ones, because you only see up to 3rd-5th cousins. If you have paid, then that kills that hypothesis.

Using both my kits as a comparison, I received my Ancestry results in June last year, and in the 9 months since then, my 4th cousin or better matches have grown from about 80 to 115 (i.e. +35). In the same period, my FTDNA  3rd-5th cousin matches have grown from to 162 to 226 (i.e. +64), so FTDNA is doing almost twice as well.

Quote
At ancestry I have made definite connectIons to 48 testers, half of them 4 to 6 cousins, half of them 5 to 8 cousins.
By contrast I have made no definite connectIons at all at ftDNA, not even from 2 to 4 cousins.
Again, my experience is different (so it is good to compare notes). My most useful match was on Ancestry, but I have had many more matches I have found helpful on FTDNA. And I find the analysis tools far better on FTDNA, but of course the trees on Ancestry are very useful - except that most matches don't have trees. at least not yet.

Quote
Don't ignore your 5 to 8 cousins at ancestry - use different methods for searching them, such as surname or place searches.
How do you use the surname or place search, and what have you learned from them? (I haven't tried this much.)

Eric, I haven't unlocked tools at ftDNA, if I can't confirm matches with any close cousins I'm not sure I will be able to do so with more distant ones!

For searching more distant cousins, way too many to look at individually -
DNA results
Search matches,Top right
Search by name or Birth location

Regards Margaret
STEER, mainly Surrey, Kent; PINNOCKS/HAINES, Gosport, Hants; BARKER, mainly Broadwater, Sussex; Gosport, Hampshire; LAVERSUCH, Micheldever, Hampshire; WESTALL, London, Reading, Berks; HYDE, Croydon, Surrey; BRIGDEN, Hadlow, Kent and London; TUTHILL/STEPHENS, London
WILKINSON, Leeds, Yorkshire and Liverpool; WILLIAMSON, Liverpool; BEARE, Yeovil, Somerset; ALLEN, Kent and London; GORST, Liverpool; HOYLE, mainly Leeds, Yorkshire

Census Information is Crown Copyright, from www.nationalarchives.go

RootsChat is the busiest, largest free family history forum site in the country. It is completely free to use. Register now.
Also register instantly with Facebook or Twitter (and other social networks). Start your genealogy search now.


Offline Guy Etchells

  • RootsChat Marquessate
  • *******
  • Posts: 3,495
    • View Profile
Re: Size of DNA data bases
« Reply #11 on: Tuesday 06 March 18 21:00 GMT (UK) »
Hi Guy,

Quote
The above figures show why DNA testing is not really worth while for genealogy yet.
You have said this before, but it simply isn't true, for most people at any rate.

Yes, the number of people who have tested is small, but consider:

1. If we consider just 4th cousins or better, which is 5 generations to the common ancestor, each tester will have 63 ancestors (except in endogamous populations). If there are 10 million testers (assuming 5 million are doubled up), then there are potentially 630 million ancestors. Now of course many of those will be multiples also, which is exactly what we want, say half of them = 315m. Virtually everyone I am connected to is in USA (330 m), UK (67m), Canada (38 m) and Australia (25m), a total of 460m. So 630m or 315m ancestors is looking pretty reasonable.

2. If we consider any one of our pairs of ancestors, the ones 5 generations back could easily have several thousands of descendants today. If we make some assumptions, for the purpose of the exercise, of how many children each couple had and how many of them had children, it is possible to make a calculation for each pair.  Assuming only 7, 6, 5, 4 and 3 children for the generations, we'd get roughly 2400 descendants for each 5th generation couple, 360 for 4th, 60 for each 3rd, 12 for each 2nd and 3 for our parents' generation. Multiply that by the number of couples in each generation and the total number of present day descendants of all our ancestors = 16 x 2400 + 8 x 360 + 4 x 60 + 2 x 12 + 1 x 3 = 41,500. If I have done the calculation correctly, that is a very approximate estimation of the total number of possible 4th cousin or better matches any of us have.  If we included out to 8th cousins as Ancestry does (which I think is not generally very useful), then the number would be absolutely enormous. So there is no shortage of potential matches. Of course I don't pretend that these figure are any more than notional, but they are illustrative.

3. And so it is no surprise that I have several hundred (only a few are repeats) 4th cousin matches on Ancestry and FTDNA out of the possible 40 thousand, or whatever the figure is, and 17 thousand Ancestry matches overall.

4. But the real proof, which you seem to have not considered, is that people are finding relatives they couldn't find any other way - adoptees, people with uncertain parentage, people whose ancestors' paper records are lost, etc. If you check out adoptee websites, you'll find plenty of success stories - and a few disappointments too!

5. In my own situation, both my maternal grandparents were of unknown origin due to an adoption, possible false names, no record of father's name, etc. DNA has enabled me to solve one of the mysteries and I have high hopes of resolving the other one day.

So a rough estimate of numbers and the real experience of many people shows that DNA is a great boon to genealogy. It doesn't solve everything of course, and it generally requires a lot of work to be done, but for many of us it is absolutely essential.

Which if you understood DNA you would realise that you do not inherit DNA form the bulk of those ancestors.
That is the difference between "pedigree ancestors" and "DNA ancestors".
Basically as you go back in time there is far more DNA available than is used to "build" a human body, yes we each inherit 50% of our DNA from our mother and 50% of our DNA from our father but that does not mean we each inherit 50% of our father's DNA and 50% of our mother's DNA.
Cheers
Guy
http://anguline.co.uk/Framland/index.htm   The site that gives you facts not promises!
http://burial-inscriptions.co.uk Tombstones & Monumental Inscriptions.

As we have gained from the past, we owe the future a debt, which we pay by sharing today.

Offline Eric Hatfield

  • RootsChat Member
  • ***
  • Posts: 143
  • Sydney, Australia
    • View Profile
Re: Size of DNA data bases
« Reply #12 on: Tuesday 06 March 18 21:56 GMT (UK) »
Hi Margaret,

Quote
I haven't unlocked tools at ftDNA, if I can't confirm matches with any close cousins I'm not sure I will be able to do so with more distant ones!
No, I can understand that. I was just checking that that is probably the reason why you only see a limited range of matches.

Quote
For searching more distant cousins, way too many to look at individually -
DNA results
Search matches,Top right
Search by name or Birth location
Thanks, I'll look into that.

Offline Eric Hatfield

  • RootsChat Member
  • ***
  • Posts: 143
  • Sydney, Australia
    • View Profile
Re: Size of DNA data bases
« Reply #13 on: Tuesday 06 March 18 23:16 GMT (UK) »
Hi Guy, thanks for sharing your thinking on this. But I think you may have some misunderstandings about DNA. I am certainly not an expert, but here is a little of what I have learnt from others.

Quote
Basically as you go back in time there is far more DNA available than is used to "build" a human body
We don't have to go back in time for that. All of us have a genome where maybe 85% is "non-coding", which means geneticists believe that those segments aren't used to make proteins or perform other useful functions.

But that isn't relevant for genetic genealogy. Testing companies typically test somewhere around 700,000 locations out of more than 3 billion. That is only about 0.02%, but these are the locations which are known to vary. All the rest stay pretty much the same. So even if all of them were tested, they'd tell us very little.

Quote
we each inherit 50% of our DNA from our mother and 50% of our DNA from our father but that does not mean we each inherit 50% of our father's DNA and 50% of our mother's DNA.
We do indeed inherit exactly 50% of our DNA from each parent, because we inherit one of each chromosome pair from each. And that inevitably means that we inherit half of each of their DNA.

The only exception to this is the 23rd chromosome, which determines gender. The X chromosome, which both genders have is larger than the Y chromosome which only men have, so a man inherits a longer length of DNA in the 23rd chromosome from his mother than his father. But that fact isn't significant to what we are discussing here.

We inherit approximately (but not exactly) 25% from each of our 4 grandparents (i.e. 2 generations back), approx 12.5% from 3 generations back, approx 6.25% from 4 generations back, approx 3.12% from 5 generations back, etc. The further back we go, the smaller the percentage and the greater the potential for variation.

Quote
Which if you understood DNA you would realise that you do not inherit DNA form the bulk of those ancestors.
So, yes, if we go back far enough we will likely not inherit discernible DNA from some ancestors. That was why I limited myself to 5 generations back, so that it is most unlikely that we don't inherit from all of those ancestors. But even if we go further back, we will still inherit discernible DNA from most of them - our DNA has to come from somewhere!

So there are always uncertainties in DNA matching. The experts say that above about 30 cM, we can be 90% confident of a match within 6 generations, whereas down at 12 cM there is little chance (5%) of such a match. The various testing companies use different algorithms to calculate matches - they tend to err slightly on the side of giving you a match to check out even if it is uncertain. But with thousands of matches, there will be many genuine matches, and most of us think it is worthwhile having to dismiss some matches that don't work out for the sake of finding the others that do work out.

So I can only conclude that you have taken an unnecessarily sceptical and not fully accurate view of DNA testing. I hope you find the links I have given helpful in building your understanding, as they have helped me. Thanks.

Offline sugarfizzle

  • RootsChat Veteran
  • *****
  • Posts: 619
    • View Profile
Re: Size of DNA data bases
« Reply #14 on: Wednesday 07 March 18 06:37 GMT (UK) »
Eric, I have looked further into ftDNA transfers (was looking for information on whether the upgrade would be worth it for me) and found the following link very interesting.

http://www.genie1.com.au/blog/82-upgrade-family-finder-transfer

"For AncestryDNA V2 (from mid-May 2016) or 23andMe V4 (from Nov 2013), you receive your immediate, close and distant matches.  You do not receive any speculative matches, which in Family Finder are those matches categorised as 4th-Remote Cousin and 5th-Remote Cousin."

It is suggesting that even if I upgraded to unlock further tools, I would still not get any increase in matches, due to the ancestry chip used from May 2016. Further on it suggests that to get the best out of ftDNA it would be a good idea to purchase the full test.

I might still unlock tools to get the chromosome browser, but if I did do another test, it would be with 23andMe to tap into their 5 million testers.

Regards Margaret
STEER, mainly Surrey, Kent; PINNOCKS/HAINES, Gosport, Hants; BARKER, mainly Broadwater, Sussex; Gosport, Hampshire; LAVERSUCH, Micheldever, Hampshire; WESTALL, London, Reading, Berks; HYDE, Croydon, Surrey; BRIGDEN, Hadlow, Kent and London; TUTHILL/STEPHENS, London
WILKINSON, Leeds, Yorkshire and Liverpool; WILLIAMSON, Liverpool; BEARE, Yeovil, Somerset; ALLEN, Kent and London; GORST, Liverpool; HOYLE, mainly Leeds, Yorkshire

Census Information is Crown Copyright, from www.nationalarchives.go

Offline hurworth

  • RootsChat Aristocrat
  • ******
  • Posts: 1,037
  • Census information Crown Copyright, from www.nationalarchives.gov.uk
    • View Profile
Re: Size of DNA data bases
« Reply #15 on: Wednesday 07 March 18 06:39 GMT (UK) »

Have you paid to "unlock" your results and the tools at FTDNA? If not (which is the case with my cousin), then I think that is why you aren't getting many new ones, because you only see up to 3rd-5th cousins. If you have paid, then that kills that hypothesis.


FamilyTreeDNA used to have a one-off fee to unlock matches if you transferred your DNA from elsewhere.  You could see your twenty top matches.  They unlocked it for all transfers about a year ago.

There is now a one-off fee of $19US per account (i.e. tested individual) to see MyOrigins and use the chromosome browser.  Paying this fee will not result in more matches.

Offline Eric Hatfield

  • RootsChat Member
  • ***
  • Posts: 143
  • Sydney, Australia
    • View Profile
Re: Size of DNA data bases
« Reply #16 on: Wednesday 07 March 18 07:38 GMT (UK) »
Margaret,

Thanks for that link, I hadn't seen it before, and even though I have been with FTDNA for two and a half years, I learnt quite a lot.
  • Yes, it resolves the question of why you only see closer matches (its Ancestry's chip, not because you haven't unlocked). Thanks for your input too Hurworth, you are right and I was wrong in my guess.
  • Yes, it shows where the different criteria of close, distant, etc, appear on the match list as you asked about and I had forgotten (not just on the chromosome browser, which I knew about).
  • And it explains why many people think that doing the FTDNA test is worthwhile even though they can transfer for free.
I really wish we knew the location of testers in the 4 main companies. I have avoided 23andMe because I thought they were mainly US based, and their testers were maybe more interested in health & medicine issues, and not so helpful with family history enquiries, but that is just an impression. I'm thinking about testing there also now, same reasons as you.

Thanks again. It is good to get clarification.

Offline sugarfizzle

  • RootsChat Veteran
  • *****
  • Posts: 619
    • View Profile
Re: Size of DNA data bases
« Reply #17 on: Wednesday 07 March 18 07:57 GMT (UK) »
Eric, DNA geek are linking to a survey at the moment, I have completed it. When results are in it might indicate the best place to get tested for testers from specific countries.

http://bit.ly/DNAMatchesByCountry

Regards Margaret
STEER, mainly Surrey, Kent; PINNOCKS/HAINES, Gosport, Hants; BARKER, mainly Broadwater, Sussex; Gosport, Hampshire; LAVERSUCH, Micheldever, Hampshire; WESTALL, London, Reading, Berks; HYDE, Croydon, Surrey; BRIGDEN, Hadlow, Kent and London; TUTHILL/STEPHENS, London
WILKINSON, Leeds, Yorkshire and Liverpool; WILLIAMSON, Liverpool; BEARE, Yeovil, Somerset; ALLEN, Kent and London; GORST, Liverpool; HOYLE, mainly Leeds, Yorkshire

Census Information is Crown Copyright, from www.nationalarchives.go