Go Back   Family Tree DNA Forums > Universal Lineage Testing (Autosomal DNA) > Family Finder Basics

Reply
 
Thread Tools Display Modes
  #1  
Old 14th January 2015, 02:20 PM
Juanita Juanita is offline
FTDNA Customer
 
Join Date: Oct 2014
Posts: 54
Half siblings vs. half aunt/niece

I have 2 females who were either half sisters or half aunt/niece. If they were half sisters, they shared the same mother. If they were half aunt/niece, the half aunt's mother was the half niece's maternal grandmother.

I have results for their 2 kits. (One, age 90, is still alive with many direct descendents, the other was childless and died recently).

FTDNA puts their possible relationship range as 1st Cousin, Half Siblings, Grandparent/ Grandchild, Aunt/ Uncle, Niece/ Nephew.

Their shared cM at on the FTDNA site is 1113.35.

GEDMatch's one-to one utility gives the following stats:
Largest segment = 68.8 cM
Total of segments > 7 cM = 1189.4 cM
Estimated number of generations to MRCA = 1.8

GEDMatch's X DNA comparison is:
Largest segment = 17.5 cM
Total of segments > 7 cM = 17.5 cM Actual.

Predicted cM value for half sibs is 1700.
Half aunt is 850.

Does anyone see something here that might point to one relationship over the other? Any suggestions on how I might get closer to an answer?
Reply With Quote
  #2  
Old 14th January 2015, 02:29 PM
dna dna is offline
FTDNA Customer
 
Join Date: Aug 2014
Posts: 2,963
I think the X match is too low for half sisters.

W.
Reply With Quote
  #3  
Old 15th January 2015, 04:47 AM
rmm0484 rmm0484 is offline
FTDNA Customer
 
Join Date: Oct 2009
Posts: 128
"Does anyone see something here that might point to one relationship over the other? Any suggestions on how I might get closer to an answer?"

How are they related on paper, if at all? What are the family stories, if any? Who might the fathers be, and how are they related to the family? You might need to flesh out the background to find the truth...
Reply With Quote
  #4  
Old 15th January 2015, 02:22 PM
Kathy Johnston Kathy Johnston is offline
Junior Moderator
 
Join Date: Jul 2006
Posts: 218
Blog Entries: 2
Quote:
Originally Posted by Juanita View Post
I have 2 females who were either half sisters or half aunt/niece. If they were half sisters, they shared the same mother. If they were half aunt/niece, the half aunt's mother was the half niece's maternal grandmother.

I have results for their 2 kits. (One, age 90, is still alive with many direct descendents, the other was childless and died recently).

FTDNA puts their possible relationship range as 1st Cousin, Half Siblings, Grandparent/ Grandchild, Aunt/ Uncle, Niece/ Nephew.

Their shared cM at on the FTDNA site is 1113.35.

GEDMatch's one-to one utility gives the following stats:
Largest segment = 68.8 cM
Total of segments > 7 cM = 1189.4 cM
Estimated number of generations to MRCA = 1.8

GEDMatch's X DNA comparison is:
Largest segment = 17.5 cM
Total of segments > 7 cM = 17.5 cM Actual.

Predicted cM value for half sibs is 1700.
Half aunt is 850.

Does anyone see something here that might point to one relationship over the other? Any suggestions on how I might get closer to an answer?
Could these two be related on another line as well? For example, did cousins mary cousins in this family? I would guess that these two were not half sibs but shared more than expected for a half-aunt because of consanguinity or endogamy.
Reply With Quote
  #5  
Old 15th January 2015, 04:05 PM
Juanita Juanita is offline
FTDNA Customer
 
Join Date: Oct 2014
Posts: 54
On paper, they are half aunt/niece. My mother, J, is the half aunt. Her birth certificate says she's the daughter of H and C. The childless, deceased half niece, L, is the daughter of G, the daughter of H from a former marriage.
The maternal line is not in doubt, as there are numerous matches along that line for J, L and other family tested.

Now the back story.*
G also had a son, R. His birth certificate predates J's by 3 weeks.*
G's husband (L's father), denied paternity of R. (Probably true)
H and C raised R while L lived with her father.

Here's the case for half sisters:

1. J and R were called 'the twins', and bore remarkable resemblance to each other. Although G was an infrequent visitor, my mother remembers G would pull her up into her lap, begin to cry and tell her, "You're my baby. You're my baby."
2. On the back of R's birth certificate, H wrote a note to G circa 1935:
The first part seems to be a list of the names and birth dates of G's children:
A borned September 29, 1920 (Died in infancy)
L borned September 19, 1922
R borned May12, 1924
J _______ ____ _______ _____*

The second part of the note reads:
“G,
I will keep J's birth certificate as I will never give her up to you as long as I am on earth. When I am gone you may have her or let Julia have her if you are not able to keep her.
Mother”
3. One of H and C's children (now deceased) told me she remembered H giving birth in 1924 to a stillborn girl. She was 6 years old at the time, and figured G had 2 babies and H had none, so G gave one of the babies to H.
4. DNA results from 2 of J's 2nd cousins on C's side, show no shared DNA.


Pretty compelling, huh? However, there are more than a few flies in the ointment.


1. L shows 111 shared cM for an 'on paper' male second cousin who should also match my mother if they were half sisters. He doesn't. Nor does another male half second cousin from that line. Both of these male cousins show a cousin relationship to each other.
2. When I run the predicted cM values for family members tested, they lean toward the half aunt/niece scenario with a few more head scratching results of their own.
3. R's birth certificate shows no sign of being amended and the county birth index shows no other birth certificate under another name for my mother.
4. How trustworthy were the childhood memories of my aunt?
5. And then as one responder pointed out, the X-DNA is a really small number for half sisters.

But isn't it serendipitous when things seem to present themselves one right after the other in a matter of days? After years of searching, I've now found one of R's (1924-66) sons and he has agreed to take a DNA test. I hope it will shed more light on all of this.

I'd still appreciate any thoughts or observations anyone might have. Meanwhile I'll look to see if there was any indication of cousins marrying.
Reply With Quote
  #6  
Old 10th February 2015, 07:55 PM
prairielad prairielad is offline
FTDNA Customer
 
Join Date: Feb 2011
Location: Canada
Posts: 2,023
What is listed under the suggested relationship column when you download their matchlist .csv file? Link is on the bottom of FTDNA FF match page.
Reply With Quote
  #7  
Old 11th February 2015, 08:29 AM
Juanita Juanita is offline
FTDNA Customer
 
Join Date: Oct 2014
Posts: 54
The suggested relationship is 1st cousin probably because the X is so low.
Reply With Quote
  #8  
Old 11th February 2015, 09:36 AM
madman madman is offline
FTDNA Customer
 
Join Date: May 2012
Location: New York
Posts: 306
Looks like 1st cousins from two sisters


Quote:
Originally Posted by Juanita View Post
I have 2 females who were either half sisters or half aunt/niece. If they were half sisters, they shared the same mother. If they were half aunt/niece, the half aunt's mother was the half niece's maternal grandmother.

I have results for their 2 kits. (One, age 90, is still alive with many direct descendents, the other was childless and died recently).

FTDNA puts their possible relationship range as 1st Cousin, Half Siblings, Grandparent/ Grandchild, Aunt/ Uncle, Niece/ Nephew.

Their shared cM at on the FTDNA site is 1113.35.

GEDMatch's one-to one utility gives the following stats:
Largest segment = 68.8 cM
Total of segments > 7 cM = 1189.4 cM
Estimated number of generations to MRCA = 1.8

GEDMatch's X DNA comparison is:
Largest segment = 17.5 cM
Total of segments > 7 cM = 17.5 cM Actual.

Predicted cM value for half sibs is 1700.
Half aunt is 850.

Does anyone see something here that might point to one relationship over the other? Any suggestions on how I might get closer to an answer?
Reply With Quote
  #9  
Old 11th February 2015, 09:47 AM
hazel_ion hazel_ion is offline
FTDNA Customer
 
Join Date: Dec 2014
Posts: 153
Figures from 23andMe Compare Genes function (from Tim Janzen's data):
Parent-child pairs share between 83.94% and 84.20% of SNPs (50% of DNA in common)
Siblings share between 83.81% and 87.47% of SNPs (50% of DNA in common)
Uncle/aunt-niece/nephew pairs share between 78.48% and 79.57% of SNPs (25% of DNA in common)
Grandparent-grandchild pairs share between 77.96% and 80.59% of SNPs (25% of DNA in common)
First cousins and great uncle/great aunt-grandniece/grandnephew pairs share 75.78% and 77.03% of SNPs (12.5% of DNA in common)
First cousins once removed share ca 75.5% of SNPs (6.25% of DNA in common)
Second cousins and first cousins twice removed share ca 75% of SNPs (3.125% of DNA in common)
Unrelated people of European descent share 73-74.6% of SNPs
Reply With Quote
  #10  
Old 11th February 2015, 09:49 AM
hazel_ion hazel_ion is offline
FTDNA Customer
 
Join Date: Dec 2014
Posts: 153
http://www.isogg.org/wiki/Autosomal_DNA_statistics
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Half-Aunt? BJackson Adoptees Forum 3 12th January 2015 07:22 PM
Half Siblings? tab1968 Family Finder Advanced Topics 11 16th May 2014 06:16 AM
Half Aunt not included in Family Finder Matches XeniaGal DNA and Genealogy for Beginners 0 16th November 2013 03:48 PM
Half Aunt MarkT Family Finder Advanced Topics 9 10th February 2012 10:27 AM
Half Uncle/Aunt vs Cousins Griot1635 Family Finder Advanced Topics 6 22nd August 2011 06:04 AM


All times are GMT -5. The time now is 05:22 AM.


Family Tree DNA - World Headquarters

1445 North Loop West, Suite 820
Houston, Texas 77008, USA

Phone: (713) 868-1438 | Fax: (832) 201-7147
Copyright 2001-2010 Genealogy by Genetics, Ltd.
Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.