DNA Kinship Testing is a broader term for an old-technology DNA test often called sibling testing. You may see additional coined terms such as “siblingship” or “sibship” testing.
This type of test compares two people on a small set of autosomal genetic markers. You inherit these autosomal markers randomly from both parents.
The test looks at something called Short Tandem Repeats (STRs). Your values on these markers may indicate a high or low probability of a close relationship.
By itself, however, an STR-based sibling test CANNOT absolutely prove or disprove a relationship.
For this reason I now consider such tests a WASTE OF MONEY..
When a lab is AABB-accredited, you can assume they’ll do the test right. But they often promise more than they can deliver. Or they do a terrible job of interpreting and reporting results.
I know this because many people have contacted me regarding their test results.
I’ve seen reports where a lab concludes—from the autosomal test alone—that two people are related or not related.
Unlike a paternity test, an STR-based sibling test does not produce obvious Yes/No answers. At best, all you can hope for is a strong "Maybe."
Worse yet, the tests can sometimes mislead you. That happened to me personally and led to a wrong conclusion about my birth father.
The far better type of test for checking a close relationship--anything out to the first or second cousin level--is a SNP-based autosomal DNA test.
Here are the two tests that I used myself with rock-solid results:
Both tests are SNP-based (not STR-based) and each one checks more than 700,000 markers. Check the above links for current pricing. You need to choose one test and then order a separate test kit for each person being tested.
See my DNA Sibling Test page for more on my personal use of DNA kinship testing.
For the most thorough explanation you need to read my new book, which tells my whole adoption search story and describes each of the five DNA tests I used to ultimately discover the truth surrounding my birth:
If you already have results from another autosomal DNA test, you may be able to transfer into Family Finder for free.