Saturday, 29 July 2017

Comparing match tallies for family members with Family Tree DNA's Family Finder test

I've taken a look at the total number of matches for all my family members who have taken a Family Finder test at Family Tree DNA. I've also done a comparison with the data I extracted on 26th May 2016 just before Family Tree DNA updated their matching algorithms. The results are shown in the table below. Note that I have excluded immediate family members from the totals.

Relation Number of matches
 28 July 2017
Number of matches
 26 May 2016
% increase
Debbie 1217 592 51%
Debbie's dad 1344 643 52%
Debbie's mum 1038 495 52%
Debbie's husband 905 443 51%
Debbie's eldest son 1138 542 52%

If my matches are representative of the wider Family Finder database then there has been over a 50% increase in the size of the database in the last 14 months.

I've also looked at the number of matches I share with my parents and taken stock of the number of matches which don't match either parent.

I share 501 matches with my dad. Of these, 320 were assigned to the paternal side with FTDNA's Family Matching tool. The remaining 181 matches were in common with my dad but did not meet the threshold for Family Matching.

I share 402 matches with my mum. Of these, 276 were assigned to the maternal side with the Family Matching tool. The remaining 126 matches did not meet the threshold for Family Matching.

I therefore have a total of 903 matches (74%) which match my mum or my dad. However, this means that 314 of my 1217 matches (26%) do not appear in the match lists of either of my parents.

All the matches that don't match my parents have a longest segment under 15 cMs. This is the breakdown.

Longest block  Number
10-14 cMs 28
7-9 cMs 286

The last time I did a comparison of parent and child matches I found that 23% of my matches did not match either of my parents.

These matches are either false positives or false negatives but without further investigation it is not possible to tell.

Have you tested both of your parents at Family Tree DNA? What are your statistics?

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3 comments:

Sam Geary said...

This site is copying all your posts and giving you no credit and making themselves the author. An example:

https://loudnaija.wordpress.com/2017/08/05/comparing-parent-and-child-matches-at-ancestrydna/

You can get a takedown notice by filling out this form:

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Debbie Kennett said...

Sam

Thank you so much for letting me know about this. I've written to the owners of the website to ask them to remove the content. If they don't comply I will send them the takedown notice.

Debbie Kennett said...

Sam

I thought you might be interested to know that I received a response to my e-mail from the blogger. He was very apologetic and has now removed all my articles from his website. I noticed that he's using content from other bloggers in his British section. I've suggested that he remove those posts as well. I've encouraged him to write his own original content instead.