What is Autosomal DNA?
The human genome consists of 23 pairs of chromosomes: 22 of them are non-sex chromosomes and the last pair are the sex chromosomes. The 22 pairs of chromosomes are the autosomes and the DNA that is encoded in them is called the autosomal DNA.
So when you take an autosomal DNA test from any of the genetic genealogy companies like AncestryDNA, Family Tree DNA, 23andMe, or MyHeritage DNA, you are getting tested for these 22 pairs of autosomal DNA in addition to X, Y and Mt DNA. The autosomal DNA is inherited from either parent and therefore their occurrences in pairs- one from the mother and the other from the father. They in-turn would have received their genes from your grandparents.