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Genealogical "Closeness"


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#1 Spencer

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Posted 05 July 2018 - 11:27 AM

"Closeness" in Genealogy.

 

For example, is a sixth cousin, 14 times removed, a closer relation than a seventh cousin, 13 times removed?

 

DSH



#2 TomH

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Posted 05 July 2018 - 11:50 AM

Consanguinity is a pre-DNA concept of closeness by blood lines. At that distance, the shared blood is so small that the difference between them, if any, is insignificant and neither is very much closer than a random person. Look up "consanguinity" in Wikipedia.

Tom user of RM7550 FTM2017 Ancestry.ca FamilySearch.org FindMyPast.com
SQLite_Tools_For_Roots_Magic_in_PR_Celti wiki, exploiting the database in special ways >>> Rmtrix_tiny.png app, a bundle of RootsMagic utilities.


#3 zhangrau

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Posted 05 July 2018 - 12:07 PM

"Closeness" in Genealogy.

 

For example, is a sixth cousin, 14 times removed, a closer relation than a seventh cousin, 13 times removed?

 

DSH

 

Here's how I look at it - but I'm not a medical DNA expert.

 

6 + 14 = 20 and 7 + 13 = 20

 

So there is no significant difference in kinship. Both examples are 20 generations to the common ancestor.



#4 Spencer

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Posted 05 July 2018 - 03:06 PM

Farblondjet.

 

21 Generations to the Common Ancestor/s.

 

Think About It.

 

DSH



#5 zhangrau

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Posted 05 July 2018 - 06:17 PM

You just couldn't resist throwing an insult, could you?



#6 Spencer

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Posted 06 July 2018 - 01:29 AM

Surely, first cousins are closer than second cousins.  N'est-ce pas?

 

And:

 

By the same logic, sixth cousins are closer than seventh cousins.



#7 TomH

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Posted 06 July 2018 - 12:18 PM

The correct statement is that the long branch is 21 generations for both the 6c14r and 7c13r relationship but the short branch is, respectively 7 and 8. Thus the distances between the relatives are:

6c14r = 7 + 21 = 28 ==> 2^-28 or  0.00000037% average shared blood or consanguinity

7c13r = 8 + 21 = 29 ==> 2^-29 or  0.00000019% average shared blood

 

These levels are indistinguishable from each other and from the general population.

 

Is this relevant to the topic of this Forum, i.e., a discussion of RootsMagic 7? Not really. RM does not report on consanguinity. However, its relationship chart can be used to count the number of links between two relatives via the common ancestor. That number is the degrees of separation and the consanguinity can be calculated from 2 raised to the negative power of degrees.

 

Hidden registers for RM's Set Relationships tool store the distances from the reference person to all other relatives for rapid display of the relationship. I've used these values for outboard utilities:

Color_Code-by_Consanguinity_Pedigree.png
 

 


Tom user of RM7550 FTM2017 Ancestry.ca FamilySearch.org FindMyPast.com
SQLite_Tools_For_Roots_Magic_in_PR_Celti wiki, exploiting the database in special ways >>> Rmtrix_tiny.png app, a bundle of RootsMagic utilities.


#8 Spencer

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Posted 06 July 2018 - 04:58 PM

Actually, there is a brilliant little program, ATMatch, developed by Ian Fettes, which runs very nicely when fed with genealogical data constructed by RootsMagic 7.5.7.0.

 

Gentle Readers will find it here:

 

http://www.genealogi...s/software.html

 

And here is a description of said ATMatch:

 

"ATMATCH

 

Do you want to compare the details of your genealogical database for a given person or family with that from another researcher?  Sound like a daunting task? This program can help!

 

This Windows program lets you compare the two family sequences. It does this by matching two separate ahnentafel lists for the same individual to identify the similarities and differences between them. I use it to compare the information in my database with that of another person to make updates easier. 

Latest version now runs under Windows up to Windows 10 properly.

Input may be direct from a GEDCOM file, or through ahnentafel listings provided from two specialist programs. 

Program features include: -

  • calculate the Wright Coefficient of Inbreeding [COI] (very fast routine) and my own Fettes Coefficient of Ancestry [COA] for the subject
  • utility routine to join Ahnentafel (AT) numbers together, using either Kekule or British number formats
  • log the differences found between the files
  • optional tagging and various matching features
Size 2.25 MB zip file atmatch1.6.zip Ver 1.60 August 2015

 

Ian Fettes

-----------------------------------------------------------------

 

I have found the program very helpful in working with RootsMagic and Family Origins -- particularly in calculating the COI and COA.

 

Here is the download link for ATMatch again:

 

atmatch1.6.zip



#9 Spencer

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Posted 06 July 2018 - 05:22 PM

It's also quite important to keep these facts firmly in mind when working with the RM7 Data and COR, COI and COA.

 

Human relationships

 

https://en.wikipedia...of_relationship

 

220px-Coefficient_of_relatedness.png
 
Diagram of common family relationships, where the area of each colored circle is scaled according to the coefficient of relatedness. All relatives of the same relatedness are included together in one of the gray ellipses. Legal degrees of relationship can be found by counting the number of solid-line connections between the self and a relative.

The coefficient of relationship is sometimes used to express degrees of kinship in numeric terms in human genealogy.

In human relationships, the value of the coefficient of relationship is usually calculated based on the knowledge of a full family tree extending to a comparatively small number of generations, perhaps of the order of three or four. As explained above, the value for the coefficient of relationship so calculated is thus a lower bound, with an actual value that may be up to a few percent higher. The value is accurate to within 1% if the full family tree of both individuals is known to a depth of seven generations.[2]

Degree of
relationship Relationship Coefficient of
relationship ® 0 identical twins; clones 100%[3] (1) 1 parent–offspring[4] 50% (2−1) 2 full siblings 50% (2−2+2−2) 2 3/4 siblings or sibling–cousins 37.5% (2−2+2−3) 2 grandparent–grandchild 25% (2−2) 2 half siblings 25% (2−2) 3 aunt/uncle–nephew/niece 25% (2⋅2−3) 4 double first cousins 25% (4⋅2−4) 3 great grandparent–great grandchild 12.5% (2−3) 4 first cousins 12.5% (2⋅2−4) 6 quadruple second cousins 12.5% (8⋅2−6) 6 triple second cousins 9.38% (6⋅2−6) 4 half-first cousins 6.25% (2−4) 5 first cousins once removed 6.25% (2⋅2−5) 6 double second cousins 6.25% (4⋅2−6) 6 second cousins 3.13% (2⋅2−6) 8 third cousins 0.78% (2⋅2−8) 10 fourth cousins 0.20% (2⋅2−10)[5]

Most incest laws concern the relationships where r = 25% or higher, although many ignore the rare case of double first cousins. Some jurisdictions also prohibit sexual relations or marriage between cousins of various degree, or individuals related only through adoption or affinity. Whether there is any likelihood of conception is generally considered irrelevant.

----------------------------------------------------------------------------------

Yes, Virginia, as one can see from the chart above, third cousins are MORE CLOSELY RELATED than FOURTH COUSINS.

 

But whoever doubted it?

 

DSH



#10 Spencer

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Posted 06 July 2018 - 05:28 PM

Degree of
relationship Relationship Coefficient of
relationship ® 0 identical twins; clones 100%[3] (1) 1 parent–offspring[4] 50% (2−1) 2 full siblings 50% (2−2+2−2) 2 3/4 siblings or sibling–cousins 37.5% (2−2+2−3) 2 grandparent–grandchild 25% (2−2) 2 half siblings 25% (2−2) 3 aunt/uncle–nephew/niece 25% (2⋅2−3) 4 double first cousins 25% (4⋅2−4) 3 great grandparent–great grandchild 12.5% (2−3) 4 first cousins 12.5% (2⋅2−4) 6 quadruple second cousins 12.5% (8⋅2−6) 6 triple second cousins 9.38% (6⋅2−6) 4 half-first cousins 6.25% (2−4) 5 first cousins once removed 6.25% (2⋅2−5) 6 double second cousins 6.25% (4⋅2−6) 6 second cousins 3.13% (2⋅2−6) 8 third cousins 0.78% (2⋅2−8) 10 fourth cousins 0.20% (2⋅2−10)[5]
 

Here's that chart more clearly expressed.  I hope it comes through this time.

 

Spencer



#11 Spencer

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Posted 06 July 2018 - 05:32 PM

No Joy...

 

Well, you can see it clearly here:

 

https://en.wikipedia...of_relationship

 

DSH



#12 Spencer

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Posted 08 July 2018 - 12:27 PM

Consanguinity is a pre-DNA concept of closeness by blood lines. At that distance, the shared blood is so small that the difference between them, if any, is insignificant and neither is very much closer than a random person. Look up "consanguinity" in Wikipedia.

 

Actually, RELATEDNESS is a far broader and deeper category than just DNA-mongering.

 

So is CLOSENESS.  You are using CONSANGUINITY as a RED HERRING here.

 

RELATEDNESS has components of CULTURE, AFFINITY, "LOOKS", HABITS, "FAMILY HISTORY", et cetera.

 

Of COURSE the Scientific Component is important and should be cultivated.

 

But just because someone is, say, a 7th cousin, twice removed, but was born in the same region as the Root Person, had similar formative experiences, may have attended the same schools and universities, et cetera, should then be rejected because the "SHARED BLOOD QUOTIENT" is too small ---- is a severely fallacious concept.

 

Further,  RootsMagic 7 is so good at DISPLAYING these OTHER components of RELATEDNESS.  Particularly with FACTS and NOTES -- far better than any other genealogical program I have found.

 

RootsMagic ENCOURAGES NOTES.  Medical Notes, Military Notes, Birth Notes, Death Notes, Career Notes, Make Your Own Category Notes,  TEXT -- which is what literate people use.

 

I have huge chunks of TEXT in my primary database -- RootsMagic's UI is most useful in doing that -- logical, intuitive and robust.



#13 zhangrau

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Posted 08 July 2018 - 04:04 PM

An algorithm to calculate your proposed CLOSENESS would be very complex. And, I'm willing to bet, will never satisfy a wide variety of interested folks.



#14 Spencer

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Posted 08 July 2018 - 06:28 PM

I haven't proposed an algorithm to calculate CLOSENESS.

 

DSH