Genetic genealogy is the use of DNA testing techniques to trace genealogical relationships. It is a rapidly growing field of study. Since 2012, more than 26 million people have taken a DNA test to trace their ancestry. This has created a valuable database for pharmaceutical companies and law enforcement.
Ancestry Painting
Ancestry Painting uses your 23 autosomal chromosomes to show you where your DNA originated from, segment by segment. Unlike other tools that look at your entire pedigree, this approach allows you to paint a picture of which regions of your chromosomes come from Africa, Asia, or Europe
One of the most useful features of Ancestry's Chromosome Painter is its ability to show you which segments of each chromosome you inherited from your grandparents. It's a great way to see which ethnic regions you may have inherited from each of your parents or from each of your paternal and maternal grandparents.
Ancestry Painting also includes a shared centimorgan tool that helps you determine how closely your DNA matches are related. This helps you discover if you have more or less DNA than expected from your tests in common with your matches. Visit this site to know more about genetic genealogy.
AtDNA
Autosomal DNA (atDNA) is one of the most popular types of genealogical DNA tests because it can identify ancestors up to 5-7 generations in the past. The test looks at more than 700,000 DNA markers on a person's "autosomes," or 22 pairs of non-sex chromosomes found inside the cell's nucleus.
The atDNA portion of a person's DNA undergoes a process called recombination, which shuffles maternal- and paternal-inherited copies. This makes it difficult to pinpoint exactly when a person's ancestors should have shared a common ancestor, but this type of testing can help confirm recent relationships.
Some atDNA tests also include Y-chromosome (Y-DNA) and mitochondrial DNA (mtDNA). While Y-DNA gives information on patrilineal descent, mtDNA helps trace a direct maternal line.
SNPs
SNPs are a type of DNA marker that can be used to trace ancestry. They can also be useful in other areas of genetic research, such as genome-wide association studies or identifying mutations associated with the disease.
SNP testing is also used to find long segments of identical DNA that are shared between two people. This can help identify genetic cousins or even a common ancestor, but not all people share the same length of DNA.
The accuracy of genome-wide relatedness methods and identity by descent (IBD) segment-based relatedness estimation tools was evaluated using simulated genome-wide SNP genotyping data. A variety of parameters were varied to test performance across data sets. These included the minimum number of shared SNPs and the maximum distance between SNPs for a segment to be identified.
STRs
STRs are sequences of DNA that contain short tandem repeats of 1-6 nucleotides, which can form series with lengths of up to 100 nt. They are found in both prokaryotes and eukaryotes, including humans. STRs are useful in studying human genetics and are a major component in genome mapping, linkage analysis, paternity testing, and disease diagnosis 50.
STRs can be affected by various mutations, including transitions/transversions and single-nucleotide insertions/deletions. Moreover, nonspecific mutations such as slippage or frameshifts often stabilize them. These mutations are less common than those of specific STR variants, but they can potentially disrupt a gene's expression by changing its nucleotide composition and mutability. Hence, they may have important roles in gene regulation and transcriptional processes.
Matching
Genetic matching is a method of nearest-neighbor matching where distances are computed as the generalized Mahalanobis distance with a scaling factor for each covariate. The scaling factors are chosen by a genetic algorithm that maximizes a criterion related to covariate balance.
DNA matches are organized according to the percentage of DNA they share with a given match. This figure is expressed in centimorgans (cM), which is the unit of genetic linkage between two people.
A longer segment of shared DNA is more likely to indicate a recent common ancestor. However, it's important to note that a match's total cM value is a rough relationship estimate.
