Autosomal DNA (atDNA) tests look at genetic markers found in the 22 chromosome pairs which contain randomly mixed DNA from both parents, basically all chromosomes except the sex chromosome, although some testing companies provide data from the X chromosome as part of this test as well.
https://www.thoughtco.com/dna-tests-available-for-genealogy-1421838
The father line is just one lineage in your family tree, and as you go further back in time it represents less and less of your total ancestry. For example, you have 64 great-great-great-great grandparents, and a Y-DNA test will only tell us about the ancestry of one of these 64 ancestors.
https://www.ucl.ac.uk/mace-lab/debunking/understanding
The chance that an autosomal DNA test will accurately detect a relative decreases with the distance of the relationship. For example, most autosomal DNA ancestry tests predict an accuracy rate of 90–98% when detecting a match with a 3rd cousin, but around a 45–50% chance of detecting a match with a fourth cousin.
https://www.thoughtco.com/autosomal-dna-testing-for-genealogy-1421845
Available To: males only. Y-DNA tests specific markers on the Y-Chromosome of your DNA known as Short Tandem Repeat, or STR markers. Because females do not carry the Y-chromosome, the Y-DNA test can only be used by males. It passes down directly from father to son.
https://www.thoughtco.com/dna-tests-available-for-genealogy-1421838
We offer three basic types of tests: Family Finder (autosomal DNA), Y-DNA, and mitochondrial DNA (mtDNA). Our Family Finder test focuses on autosomal DNA, which is inherited from both your mother and your father, your four grandparents, your eight great-grandparents, etc.
https://www.familytreedna.com/learn/ftdna/our-three-basic-tests/
There are different levels of Y-DNA matches available. Picture Y-DNA as a puzzle with 111 pieces to it. Whatever level of Y-DNA you have, it compares that number of puzzle pieces, or markers, to another person’s to see how many markers you have in common.
https://www.familytreedna.com/learn/ftdna/our-three-basic-tests/
We offer three basic types of tests: Family Finder (autosomal DNA), Y-DNA, and mitochondrial DNA (mtDNA). Family Finder. Our Family Finder test focuses on autosomal DNA, which is inherited from both your mother and your father, your four grandparents, your eight great-grandparents, etc. We call our ethnic breakdown myOrigins.
https://www.familytreedna.com/learn/ftdna/our-three-basic-tests/
I scrolled through it. Ancestry.com has me having 25 chromosomes, two alleles of each. The normal human being has 23 chromosome pairs, including the sex-determining chromosomes. So, I am either a new species of human being carrying 2 more chromosome pairs than the rest of the human race, or, Ancestry.com's autosomal DNA testing is flawed.
https://www.ancestry.com/boards/thread.aspx?mv=flat&m=259&p=topics.dnaresearch.autosomal
Your parents, in turn, received their chromosomes from their parents (your grandparents). Your autosomal DNA, therefore, contains random bits of DNA from your great-grandparents, great-great grandparents, and so on. Close relatives will share large fragments of DNA from a common ancestor.
https://www.thoughtco.com/autosomal-dna-testing-for-genealogy-1421845
Genetic ancestry testing is the use of DNA information to make inferences about someone’s deep ancestry, hundreds or thousands of years into the past. Genetic genealogy on the other hand combines DNA testing with genealogical and historical records, and typically makes use of large databases to identify matches.
https://www.ucl.ac.uk/mace-lab/debunking/understanding
how many chromosomes does ancestry dna test for
The AncestryDNA tests for 22 chromosome.