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Forum: Y-DNA Haplogroups & SNPs Basics 21st May 2018, 08:27 AM
Replies: 112
Views: 13,347
Posted By John McCoy
Naming children after different saints, for...

Naming children after different saints, for example John the Evangelist and John the Baptist, is certainly a possibility, but these cases are found in a period when baptisms were not recorded (in my...
Forum: Y-DNA Haplogroups & SNPs Basics 20th May 2018, 01:54 PM
Replies: 112
Views: 13,347
Posted By John McCoy
Regarding multiple children of the same father...

Regarding multiple children of the same father who bear the same baptismal name, there are numerous examples at least as late as the 16th Century. Working with (Latin) medieval documents in...
Forum: DNA and Genealogy for Beginners 19th May 2018, 03:11 PM
Replies: 8
Views: 247
Posted By John McCoy
I don't understand where you are finding numbers...

I don't understand where you are finding numbers such as 46/31 or 50/30. We need some context.
Forum: DNA and Genealogy for Beginners 19th May 2018, 11:48 AM
Replies: 6
Views: 287
Posted By John McCoy
There are at least a couple numbers floating...

There are at least a couple numbers floating around for the probability of 4th cousins matching by default criteria. The 50 percent number is widely quoted, but I believe I've seen 25 percent (the...
Forum: Paternal Lineage (Y-DNA STR) Advanced 17th May 2018, 06:42 PM
Replies: 9
Views: 307
Posted By John McCoy
I have only a few Y-67 matches that could...

I have only a few Y-67 matches that could possibly be considered "close". I believe the closest one ever found is GD=4. Those "close" matches turned out to be on nearby but distinct branches of the...
Forum: Grumbles & Gripes 17th May 2018, 06:37 PM
Replies: 6
Views: 215
Posted By John McCoy
I would be very suspicious too. If you're not...

I would be very suspicious too. If you're not missing a kit, ignore it.
Forum: X-DNA Advanced 15th May 2018, 12:22 PM
Replies: 31
Views: 853
Posted By John McCoy
In these situations, shared cM and even shared X...

In these situations, shared cM and even shared X chromosomes give you a limited set of possible family trees, rather than absolute proof. The next step is to find additional evidence, both...
Forum: Y-DNA Haplogroups & SNPs Basics 15th May 2018, 12:12 PM
Replies: 35
Views: 1,069
Posted By John McCoy
Absent very complete documentation, it is very...

Absent very complete documentation, it is very difficult, if not impossible, to prove that Y DNA matches are NOT related within 8 generations. Hence, I don't think we have a sound basis for...
Forum: BIG Y and SNP Discovery 10th May 2018, 10:35 AM
Replies: 4
Views: 320
Posted By John McCoy
For most SNP's, I think the prevailing theory is...

For most SNP's, I think the prevailing theory is that "equivalent" SNP's (at the same node on the current haplotree) arose as independent mutations (and I don't immediately see how that idea could be...
Forum: Paternal Lineage (Y-DNA STR) Advanced 10th May 2018, 10:20 AM
Replies: 5
Views: 412
Posted By John McCoy
Matching someone with distance zero (meaning, an...

Matching someone with distance zero (meaning, an exact match, no differences) when both of you have taken the Y-111 test is definitely significant! However, it remains possible that the common...
Forum: Features Requests & Bug Reports Area 4th May 2018, 05:14 PM
Replies: 2
Views: 158
Posted By John McCoy
As counted by most vendors, siblings will have...

As counted by most vendors, siblings will have about 2600 cM shared. The numbers depend on which version of the human genetic map is being used, and likely some additional assumptions. Parent and...
Forum: Recreation Room 3rd May 2018, 02:14 PM
Replies: 28
Views: 1,652
Posted By John McCoy
Technically, any lab that uses an appropriate...

Technically, any lab that uses an appropriate "chip" should be able to generate SNP data that can be formatted in a way that GEDmatch can read.
Forum: Features Requests & Bug Reports Area 3rd May 2018, 12:16 PM
Replies: 15
Views: 806
Posted By John McCoy
In my experience, having 4,000 matches is not ten...

In my experience, having 4,000 matches is not ten times better than having 400 matches. The additional 3,600 matches are all extremely weak, distantly related, and genealogically useless. Even the...
Forum: myOrigins Basics 2nd May 2018, 04:03 PM
Replies: 9
Views: 409
Posted By John McCoy
There may be some confusion about what can be...

There may be some confusion about what can be detected by different tests.

The "five generations" threshold MAY refer to the limit at which actual cousins can be reliably detected as autosomal DNA...
Forum: DNA and Genealogy for Beginners 2nd May 2018, 09:18 AM
Replies: 3
Views: 250
Posted By John McCoy
Absolutely! Two points here: First, the FTDNA...

Absolutely! Two points here: First, the FTDNA relationship estimates of 2nd to 4th cousins and beyond seem to be excessively optimistic most of the time. Very, very few of my matches in that range...
Forum: Family Finder Advanced Topics 1st May 2018, 01:06 PM
Replies: 17
Views: 947
Posted By John McCoy
... or, a third possibility, that some unknown...

... or, a third possibility, that some unknown relative of yours will never participate in some horrendous crime!
Forum: Recreation Room 29th April 2018, 10:40 AM
Replies: 28
Views: 1,652
Posted By John McCoy
This thread is now firmly in the realm of...

This thread is now firmly in the realm of speculation. I believe several different stories may have been conflated, and some important facts and legal procedures have been omitted. Please check...
Forum: X-DNA Basics 28th April 2018, 03:52 PM
Replies: 8
Views: 1,210
Posted By John McCoy
I agree! FTDNA and other vendors could do a much...

I agree! FTDNA and other vendors could do a much better job of putting some plain-language context around the results. A novice who is dumped into genetic genealogy will lack context, which, in...
Forum: Family Finder Advanced Topics 28th April 2018, 10:05 AM
Replies: 2
Views: 243
Posted By John McCoy
I have dozens of weak matches (generally single...

I have dozens of weak matches (generally single segments under about 25 cM), some of them matching each other, from England, Ireland, Scotland, Australia, and New Zealand, but the genealogical...
Forum: DNA and Genealogy for Beginners 27th April 2018, 05:22 PM
Replies: 3
Views: 313
Posted By John McCoy
The chromosome browser gets you halfway to true...

The chromosome browser gets you halfway to true "triangulation" -- that is, proving that you and at least two of your matches do in fact share the same piece of a chromosome. When that condition is...
Forum: Grumbles & Gripes 27th April 2018, 12:49 PM
Replies: 3
Views: 257
Posted By John McCoy
I agree! The "Message Boards" at Ancestry.com...

I agree! The "Message Boards" at Ancestry.com require only a user ID and a password, not a paid subscription. They can also be accessed in the same way through rootsweb.ancestry.com -- because they...
Forum: DNA and Genealogy for Beginners 22nd April 2018, 04:19 PM
Replies: 6
Views: 333
Posted By John McCoy
I don't see how the leap to assigning both you...

I don't see how the leap to assigning both you AND your match to an "endogamous group" got into the conversation, with no background to suggest that that is actually the case for either of you. It...
Forum: DNA and Genealogy for Beginners 22nd April 2018, 12:40 PM
Replies: 6
Views: 333
Posted By John McCoy
The total centiMorgans (cM) shared, as measured...

The total centiMorgans (cM) shared, as measured by the major vendors by their own criteria (which normally means that only segments above some minimum size are included in the total), turns out to be...
Forum: Family Finder Basics 21st April 2018, 05:12 PM
Replies: 4
Views: 900
Posted By John McCoy
Y DNA tests and autosomal tests are not looking...

Y DNA tests and autosomal tests are not looking at the same DNA, and have different uses. If your research goal is to identify a likely patrilineal origin for your father, Y DNA testing is an...
Forum: Family Finder Advanced Topics 21st April 2018, 10:17 AM
Replies: 9
Views: 503
Posted By John McCoy
You are correct, the average rate of...

You are correct, the average rate of recombination is significantly higher for human females compared with that for human males. The standard maps used for genetic genealogy use the average of the...
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