Forum:Methodology revolution of DNA and implications for this wikia

Forums: Index > Watercooler > Methodology revolution of DNA and implications for this wikia

(Note that Mak later changed his user name to Phlox.)

It seems to me that the standards of extreme rigour necessary for teasing out the fact from the fiction in dearly held beliefs/ "family lore" about descendants would require this site to become less of a community site, and more a land where only the truly scholarly macho folks dare post anything.

I guess it rather depends on what you are interested in doing. Most folk doing genealogy are quite content just to get a lineage down that they think is theirs. I doubt anyone is intested in knowingly having a bad lineage, but most probably don't look too closely at the underpinnings of what they believe to be true. Its a very egalitarian hobby. Anyone can do, and unfortunately (perhaps) do. About 1% of the genealogists pursue things with a vigorous technical approach. They tend to honk off the other 99%. But I suspect the wiki is a mansion of many rooms, with a place for everyone, irrespective of approach. Bill 02:10, 4 September 2007 (UTC)

My observation is that the increasing cheap Y-DNA (male line) and mitochodrial mt-DNA (female line) tests revolutionize the standards for accepting data on parentage. Now, folks can post what they heard from grandmothers, etc. and post it as such. Later, ancestors can come along, do the test and if they get a positive match, then much more credence can be give to what would previously been regarded as unsubstantiated myth.

Anyway, it is my intention to document where I am getting information but not get hysterical about securing the primary source material just yet. If I can verify via DNA testing some of these connections, I can go deeper into the family tree a lot lot faster.

-Mak 23:58, 2 September 2007 (UTC)

Well said, Mak! Even with DNA work, there are drawbacks, including substantial room for error. What Granny said may contain at least a quarter-truth and can lead us in the right direction. Robin Patterson 12:09, 3 September 2007 (UTC)

The drawbacks are that it is only good for Verifying pure male (son to father to grandfather but not son to mother to grandfather) or with mDNA, pure female lines. As for accuracy, a 25 marker match with a relative is as strong as the strongest case made with the most stringent standards for documentation. At the end of the day, it is as the proverb goes: Maternity is a matter of fact. Paternity is a matter of opinion. Well, maybe not anymore. As for non paternal events, well- most of these folks are dead and buried and there are no feelings to hurt, so ok some of the fathers may have not been the real fathers. Big deal.

Well, perhaps not a big deal to you, but I know folks who are intensely troubled by some of the revelations that have occurred in their family history for ancestors dating back into the early 1800's, and in one case into the early 1700's. It may not bother you, and it does not bother me, but it does bother some folks. Bill 02:04, 4 September 2007 (UTC)

Point taken. Many are interested in genealogy because they are sort of into ancestor worship in a way- that is they feel that it is important to amplify the respect and rememberance of the great things that our ancestors did. We want to assume the best of our ancestors, and there is a temptation to avoid any cognitive dissonance that conflicts with our grand pictures of them. In my opinion, being realistic about what they did brings us closer to their humanity, keeps them alive in a way. The good and the bad. You turn them into idols, and they become like stone- They are made immovable with the fantasies we ensnare them in- they can no longer speak to us. They are dead. -Mak 09:51, 4 September 2007 (UTC)

Yes, for some, there is a certain amount of ancestor worship. Indeed, in some cultures I can think of genealogy is an important adjunct to the formal religious practice. The Mormon's are an obvious example, but I'm really thinking of other cultures where ancestor worship IS the religion. And I've had conversations with one genealogist (whose contributions to our family studies I highly value) for whom the received knowledge of the family was all important. Indeed, this individual made it quite clear that if we DID learn something that contradicted the received knowledge, he was not interested in hearing about it. It was more important for him that his understanding of his family connections remain intact, than that those connections be accurate. Its a view I do not share, but it is his view, his choice, and I respect his preferences. Bill 12:59, 4 September 2007 (UTC)

Wow. He didn't even want to see the data?

No. It wasn't relevant to him. There's a quote I like that goes something like "For those for whom facts matter, faith is irrelevant; For those for whom faith matters, facts are irrelevant, or relevant only to the extent that they support faith." Both worlds view the other with almost total incomprehension. Bill 23:39, 4 September 2007 (UTC)

Coming from a science/ engineering background, that sort of reaction never ceases to surprize me. Anyway, but to be fair about the Mormon case, it really isn't ancestor worship.

The reference to Mormon's was that "in some cultures...genealogy is an important adjunct to the formal religious practice. Not meant to imply that the Mormon view included ancestor worship. I understand their preoccupation with genealogy is for purposes of saving their ancestors souls, and not ancestor worship per se. Bill 23:39, 4 September 2007 (UTC)

I am not Mormon, but as I understand it, they believe in baptism for the dead (something also practiced by the Mandaeans of Iraq and some neo-Apostolic congregations of Europe. As far as I understand it, the gist of it is that descendants are entitled to baptise their ancestors by proxy. The consequences of them not doing this for un baptised ancestors is that they will suffer some sort of purgatory, so Mormons who reverently believe this sort of thing are highly motivated to find these connections out of concern for the welfare of their dead relatives. I suppose it is sort of the moral equivalent as if you passed by a burning building with people screaming from the windows and you did nothing. The wikipedia:Baptism for the dead article notes that the practice as performed by mormons does not absolutely require a descendant, so the baptism I suppose would not be invalidated by a later discovery about a non paternity event like adoption or infidelity. There appear to be a heck of a lot of very motivated Mormon genealogists, and they are doing a great service. I see that their religious context is motivated to err on the side of ignoring information that contradicts a connection. Just to be on the safe side and all that. Other devout mormons might feel that accuracy is totally essential, because of the notion that baptism by a non descendant might risk invalidating the baptism, and thereby dissuade a true descendant to have the thing performed. But I haven't actually heard of discussions that such baptisms can be made illegitimate this way- so my view is that their overall bias is to cast the net wide. Which is fine for me- their familysearch site has been an invaluable aid. I'm happy to cast wide then verify by DNA. If I have that wrong about Mormons, anyone feel free to correct me. -Mak 23:16, 4 September 2007 (UTC)

It will be a big deal for motivated researchers though. One gal on NPR's science friday was saying that their data so far using these markers is that non paternal events are detected for 15% of the cases. Seems small, but statistically it adds up when you are going back 8 or 9 generations. What happens to my interest in Messerli family ancestors in 17th century Switzerland when I find out that my great great great grandmother was not baking pies while grandpa was in the fields?

Oops- correction, what the authority (Megan Smolenyak) actually said was that what her group has found is that 2/3's of the genealogy projects studied so far had Non paternal Events (NPE)'s that were uncovered by DNA testing. Two thirds!!! That's a shocker, but man, this is really shaking things up.-Mak 23:16, 4 September 2007 (UTC)

One thing that is not clear to me is if it is possible to quantify the degree of uncertainty created over several generations when very large marker sets that are currently available (eg 65). If you could, it would be nice so that folks could say- "well, we have only a few recollections recorded for this parentage, but the dna match indicates a probability of 85%, so that's good enough. -Mak 20:04, 3 September 2007 (UTC)

I haven't seen the statistical projections for the 65 marker tests, similar to those readily available for the 12, 25 and 37 marker test. I would guess, though, that the improvement it provides is a little less than double that obtained for the 37 marker test, based on earlier projections of what it would take to get a commensurate improvement in confidence. However, are you really happy with being wrong 15 times out of a hundred? Bill 02:04, 4 September 2007 (UTC)

What I meant was that matching is really not a boolean condition. The more markers that don't match, the lower the probability of a recent common ancestor, but it's only a probability. With a complete match, there is extremely high confidence in a close common ancestor. You can take that to the bank- no doubts about non paternal events there, that no amount of paperwork can ever disprove in a million years.

Are traditional genealogical methods obsolete? Of course not. Because though you may have established that you have close common ancestors, you may be related by means of a common father or grandfather. Only honest rigorous research can take you to the finish line.

There is a paper of interest on the DNA:Riggs page. Contrary to intuitition, the larger number of markers doesn't do much for the accuracy between two given individuals. It does have a use though, and it would be good for folks to get large sets if they want to research deep pedigree trees. A larger number of markers gives a better footprint from which to establish a common denominator signature determined from known ancestors established through traditional genealogical means.-Mak 09:32, 4 September 2007 (UTC)

The issue with increaseing the number of markers is related to cost-benefit. It roughly takes a doubling of the number of markers to get a commensurate increase in confidence. YOu get substantial improvement in adding an additional 13 markers when you go from 12 to 25, but you don't get quite the same level of improvement if you add another 12 markers going to 37. To get the same level of improvement you need to add an additional 50 markers. The net effect is that commensurate levels of improvement are progressively more and more expensive. At an early stage in the evolution of this FTDNA was recommending 37 markers because it got you the most bang for the bucks. They added the 62 marker test, I suspect, simply because people wanted more. Haven't been many takers on that, probably because of the cost.

I would guess that the cost will drop as demand for DNA testing increases---do to more factors than genealogy. At some point a DNA test at the Doctor's office is going to be a routine part of a check up. When that happens, I think we can expect that the volume will drive down the test cost t the point where $100 will get you far more than a simple YDNA test of 67 markers. It will be several years more before this gets to be routine, but it will happen. Then we will have a field day. Among other things, the specialized haplogroup and haplotype testing will become trivial (I hope). I'm not much interested in the deep genealogy that's embodied in the haplogroup results, but as it turns out that kind of data (specifically from the actual STR types of tests) can real condition and inform YDNA matches---I know of one case at I think 37 markers, where a one-off rusult with the same surname, could be rejected because haplotypes mismatched. (Haplotypes tests are based on different suites of markers than the YDNA test itself; the folks at FTDNA can usually guess as to what haplogroup/type is involved based on the 12 marker test results, but its a guess. In this case, I was fortunate that there were actual STR haplogroup test results.) Bill 12:59, 4 September 2007 (UTC)

Bill- I think this is a wave that could very well surge over, and if we play it right, Genealogy Wikia can ride that wave. YSearch and YBase databases may be good for the matching, but I think people need to be coming here to get the encyclopedic treatment of the connections they will newly be discovering.

The obvious things folks will do first is to find out more of their connection with famous people. I copied over the DNA list article of famous folks, and as you may have seen, I made a template for visually presenting similarities/differences. I'm not really convinced this is the best way to make comparisons, eg, the table at [1] seems to do a decent job, but I also know that folks are turned off by rows of numbers. Anyway, we really do not want to do marker encoding the way WP is freely encoding them in tables. It would be real nice if the data were encoded using a template, so that data is in a Nomalized form. Makes it easy to do multiple tranformations. Like for example, I can trivially add a table output option like the way the sekybrocks site did it. Authors can then just copy paste the whole list of numbers and just change the options to get the display they like for their page. -Mak 23:16, 4 September 2007 (UTC)

Linking within this wiki

Hello everyone, I have just found this wiki and am quite keen on getting it working for DNA, but it does not seem to have gone far in that direction yet. Is there any other place where this is being discussed? I think a wiki has great potential to integrate DNA and other genealogical information in a way that other media do not, but how exactly? I suggest we put aside mt DNA to start with and focus on male-line Y DNA, which is the most commonly used by genealogists. If we work out a format for linking entries who should share approximately the same Y DNA, then this can be extended to mt DNA, and potentially eventually even autosomal DNA. --Andrew Lancaster 21:28, 17 June 2008 (UTC)

Here is a proposal to perhaps get some concrete discussion going. For any individual with a descendant or seeming descendant that has a test which would be relevant to that individual, a standard section could be included. For example: This person has an apparent male line descendant (or descendants) who has been tested for the following Y chromosome markers, giving the following results. The person tested was a son/grandson/etc of (reference to the most recent individual in the line with a wiki entry).--Andrew Lancaster

Sounds good. We could start with a Template:Male descendants worded as above, maybe in infobox form or maybe just producing a heading and standard intro text that people could append their info to. Where do you suggest that this "standard section could be included"? Robin Patterson 05:01, 27 June 2008 (UTC)

I am not sure it really matters where? I guess the main thing is to try to keep a certain level of standardization in the format so that users will be able to understand and also recreate similar sections.--Andrew Lancaster 13:57, 27 June 2008 (UTC)