McDonald Analysis

This feature gives a “painting” of the testee’s 22 autosomes and the X chromosome which are "color coded" to show the "continental" ancestry found at places along them. This test is very important for people with small amounts of ancestry from a “continent” differing from their major ones. It can detect, just for example, as small as 0.4% Native American in a pure European or a mixed Afro-(Euro)American person even if the test described in #1 above cannot. Such results will be mentioned in the text. In the specific case mentioned above the American comes out of the European part. 3) Average Location of All Ancestry Here the data

(as computed from number one above) is plotted as a summary. The green spot represent the average location of all ancestry except Native American and Oceanic. Note that for people with significant sub-Saharan African ancestry this green spot is essentially meaningless. But for people with just European, Mideast, and sometimes South Asian ancestry it is usually quite accurate as far as their average ancestry goes. The “chromosomes” plot just shows which geographic region each part of each chromosome is most likely to have come from. Since everyone has two copies of each chromosome (except males for the X), they may be split in half. But note that while distant regions such as Europe and Africa split cleanly, nearby ones like Europe and the Mideast don’t.  As a result often southern Europeans will show some Mideastern spots without having recent ancestry from the Mideast. Mideasteners, especially from North Africa often have sub-Saharan African regions, as do Mediterranean Europeans. Small regions (< 2 Mb) are often just “noise. I have special tests that can sometimes tell whether they are or not, and that will reported in the text if significant. Small regions may not show on the “quantitative” lists and will also be discussed if significant. It is important to remember that this plot cannot tell father from mother in any way.

4) PCA scatter plots

These plots are labeled with comparison populations and a crosshair icon representing the testee.  This is called the PCA (Principal Component Analysis) "scatter" plot. See below for how to read these. The computer generates several dozen of these, and I send only ones of interest for whatever makeup the test person is. There are a couple of special ones that test for specific ethnic ancestry. The most common of these is for Jewish, but others exist for such ethnicities as Sardinian, Kalash, Pygmy, and certain Native American tribes. None exist, unfortunately, for East Asian ethnic people.

The PCA “scatter” plots are the result of a calculation across the whole genome (all the chromosomes except the X) and report the average ancestry. If a person’s ancestry is from one place that will be reflected on them directly. There exist dozens of possible plots but only the most informative ones are sent. In Europe and the Mideast the position on the main plot directly indicates geography. Otherwise, it is indirect. This is taken into account when the spot(s) on the map plot are calculated.The map plot shows each continent’s average location, as well as an overall average (green) excluding the American and Oceanic ancestry. Mixed Ancestry and Related Details Now if someone is of mixed ancestry, as said earlier, the spot(s) on the map, as well as PCA plots indicate the average. The quantitative lists (which sometimes are not sent if it is just one line like the common “English 100%”) represent possible combinations which average to the correct spot on all the PCA plots. Each line in the list is one set of possible combinations. We fit to 9 of the PCA plots, including ones sent and unsent.  This is a “least squares fit”. A person, to fit, has to have the same weighted average position on all 9. Thus, say somebody lies in Romania on a Euro and Mideast only “main” one. They might actually be Romanian, or could be 60% Hungarian and 40% Jewish, or 75% French and 25% Iranian, or something more complicated. On ot

her of the plots (not usually sent) however, Romania does not lie directly between Hungary and the Jews or between France and Iran, so the program (or an experienced person simply looking at a pile of plots) can tell what is correct. Well, most of the time it can but not always. For these cases, especially Jewish ancestry, I sometimes have separate special tests, whose results are reported in words. People may wish to know  “how far back in time do my tests go?” The answer is “forever”, in the sense that my tests all discuss single or mixed modern populations. For example modern populations such as North African ones can be mixtures several older ones (such as middle eastern and sub-Saharan African). This ancient mixture will appear on the chromosome plots. A similar situation exists with the Jews who are, on a long time scale, mixed Euro-Mideast. They will usually show spots of both Euro and Mideast on the chromosomes, even though we classify Jews as Mideastern. If your parents are a typical English person and a typical Jew, that mix likely will appear on the list. But a mix of  Irish, British, Romanian, and Palestinian could also appear, since these two possibilities share the same ancient roots. The spot on the map would be similar. Small or modest amounts of, for example, Mideast or Eastern European in a basically English person can appear in the list to simply indicate that the person is from a point on the map east of England, such as Normandy, Germany, or Poland. Similar things happen on and across all continents, even Euro-East Asian.  For example 97% European and 3% Han Chinese might simply be indicating a small eastward displacement on the map of the European component. If such a mix is truly recent, it almost always appears as such on the chromosomes. If ancie nt, it may or may not appear there. This fact is always very important to remember when interpreting the “quantitative” data listing.