23andme Matches and Reports trying to understand them...
I am working with someone who tested with several labs including 23andme. So these questions relate at least to the tests from the same lab.
On their reports, 23andme has a designation of half on some chromosomes and complete on others. (Complete not the word full)
In various places on their website I found the following information:
>23AndMe’s criteria for matching segments are a distance of 7cMs and at least 700 SNPs for the first segment and for segments of other people you are sharing with.
>The start and stop positions of the 23AndMe test are usually rounded to the nearest millionth base pair in Family Inheritance, while the length of matching segments is rounded to the nearest tenth of a cM.
>Relationship Average % DNA Shared
Full Sibling ............... 50%
Half Sibling............... 25%
>When you are dealing with siblings, some of the values are fully identical regions and some are half identical regions. The fully identical regions should be counted twice, but in some cases, they are not, they are only counted “as” at match, not as a match to each parents, so counted twice. (my note: is complete fully identical regions?)
>In some cases, where you match both sides is counted at 1 match and in some cases, it’s counted as 2, one for each side. The easy way to tell if someone is a full or half sibling is that full siblings have fully identical regions (FIR) and half siblings do not, because they only match ONE parent. (the report does not indicate FIR but has half and complete under a column heading of "Identity" once again complete not full)
In our situation:
>"B" and "C" share 52% DNA in common;
>"B" and "A" share 47.7% in common; and
>"C" and "A" share 54.4% in common.
By total CMS they should be full brothers:
>"A" to "C": 2871 cms;
>"A" to "B": 2643;
> "C" to "B": 2897.
When these 3 people are matched to a "cousin D" they match as:
>A to D 354 cms 12 segments using Bettinger tool Half 2ndCousin Half 1st Cousin, 2nd Cousin, Half First Cousin 1 Removed, 1st Cousin 1 Removed, Half First Cousin 2 Removed, 1st Cousin 2 Removed,
>B to D 917 cms 19 segments using Bettinger tool 1st cousin
>C to D 713 cms 15 segments using Bettinger tool 1st Cousin or Half 1st Cousin, 1st Cousin 1 Removed
All of which is confusing because there seems to be a more distant relationship with one of the siblings but if they are full siblings shouldn't the relationship with each one be basically the same?
(Jillian is that easier to read?)