DNA Analysis

pinkypinky wrote: »

Well, think about this way: what do you hope to gain from the test?

If you're looking to find close relatives, you're better off employing more traditional methods of genealogy unless you're adopted.

If you've already done the usual methods, well, DNA is a new tool in your belt and it can help you find more distant cousins. I think FTDNA has more Irish people in its database at the moment.

To give you an idea: I tested on Ancestry and the closest matches were a first cousin once removed and a second cousin, both of whom I know personally.
On the next level, a few new matches, some of whom responded to messages and some who didn't. I've been able to figure out the area they descend from on my tree in most cases.

I also tested on FTDNA: uncovered a new third cousin which lead to a whole extra branch in Australia. I had her great-grandmother on my tree but had not investigated what happened to her.

Gedmatch (third party) has ultimately led to the best results: uncovering a family mystery.

pinkypinky wrote: »

Definitely just do your parents first.

JDERIC2017 wrote: »

Hey, can anyone work this out.

I have found a relation(William) through ancestry DNA, my great grandfather is William's grand uncle what does that make William to me?

Thanks

p15574 wrote: »

Interesting story here, although presented in a very annoying fashion, about 40 pages with a couple of sentences per page - I think it's designed for a presentation. Basically, after about 30 pages, you find out that identical triplets each did a DNA test and got different results, even though they had previously confirmed they had identical DNA.

RGM wrote: »

I imagine the results of a study like that in any rural Irish village would be much more interesting, at least in terms of how many people are related to other people. Everyone would be related to everyone.

spurious wrote: »

I taught in an inner city school and once had a class where out of 21, 18 were cousins with at least one other person in the class. All it takes is a couple of big families.

ROH

The observation of a subtle degree of isolation for the Irish group at the LD level is also in agreement with the results of our ROH analysis. Again we see very similar patterning across populations, but our results suggest that the Irish population has the largest proportion of the genome in ROH (as measured by FROH1), relative to the British and HapMap CEU populations examined here (Figure 3). Overall, the Irish and Swedish populations seem slightly different from the others in the context of ROH. Both the Irish and Swedish populations showed, on an average, a greater number of ROH, an increased maximum ROH length, as well as an increased proportion of the genome in homozygous runs, compared with that of the Scottish, southern English and Utah populations. Similarly, the mean level of individual autozygosity per population as measured by FROH22 was highest for the Irish group (Figure 4). Together, these results suggest slightly increased autozygosity in the Irish cohort compared with the British and Swedish cohorts.

Autozygosity is generated by increased levels of kinship, which in turn reflects the population history of Ireland. Although relatively undisturbed by secondary migrations,5, 26 the population of Ireland has undergone expansions and contractions at numerous points in recent history (eg, two major famines since 1600, disease epidemics, expansion in the first half of the 19th century). Aside from these features, the increased autozygosity may also reflect legacies of Gaelic family structures and comparatively low levels of migration that are in part due to a lack of industrial revolution in Ireland.

To test a hypothesis of increased autozygosity due to features of relatively recent population history, we examined the patterning of homozygosity looking for signals of parental relatedness over the last four or five generations. Previous work has illustrated that parental relatedness arising within four to six generations predominantly affects ROH over 5 Mb in length.22 We therefore compared this statistic across populations. Results show that the Irish and Swedish populations have around 10 times as much of their genomes in ROH over 5 Mb in length than the southern English, and 1.5–3 times as much as Scotland and Utah (Figure 4).

Ireland remains as the population with the most homozygous runs and the longest sum length of homozygosity. This provides further evidence that the elevated proportion of shorter ROH, and hence the number of ancient pedigree loops in Ireland, is indeed real and not driven by a limited number of offspring of cousins.

Famine and mass emigration may have driven the increased levels of autozygosity in the Irish population. However, we consider it likely that the increased levels we have observed are at least partially attributable to the genetic remnants of ancient Gaelic patrilineal dynasties,33, 34, 35 in combination with the traditionally agricultural nature of Irish society. Ireland was not affected by industrial revolution to the same extent as Britain. Industrial revolution has been associated with mass migration from rural to urban communities and an expansion of effective population size. The absence of such a pattern in Ireland would have resulted in an extended adherence to primogeniture-style inheritance of land, with frequently only one adult sibling from each family being enabled to marry and reproduce by accession to farm ownership. Such patterns would have restricted growth in effective population size. However, a potential confounder in this study is the sampling scheme: at least in areas with little mobility, recruiting primarily from rural as opposed to urban areas could increase levels of autozygosity, as could sampling a group of people who were born earlier.36

Similar to Ireland, Sweden has also traditionally been an agricultural society. Although the industrial revolution drove urbanization in Sweden towards the end of the 19th century, the more recent time to population bottleneck (as indicated by the LDU map) and the resulting rapid expansion during the 20th century might be contributing to the lack of diversity we observe in our data. Further, work taking these variables into account will be necessary to fully understand the causes underlying the patterns we see.