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It was realized in the 1940s that DNA molecules are passed down through the generations of a family. In 1953 Watson and Crick elucidated the chemical structure of this molecule as a twisted ladder (a ‘helix’) made of two strands. DNA occurs in all the cells of our body, it is our blueprint! The strands of DNA contain information in the form of a code, which in turn determines our individual traits and characteristics. This code, the genetic code, is the order of four types of DNA building block. When the two strands of DNA separate, each building block (‘base’) accurately templates a corresponding base on the newly made strand of DNA so that information is not lost but is instead duplicated and preserved.

Testing for similarities between DNA (deoxyribonucleic acid) samples from two people allows family relationships to be established – or disproved – to an extraordinarily high degree of certainty. A common use for a DNA test is to establish if a man is the biological father of a child; this is known as a paternity test. However, there are other uses for the science of DNA testing (also called genotyping), these include forensic analysis of human DNA samples, and tracking relationships amongst domesticated animals.

The order in which the bases occur in DNA is referred to as the DNA sequence. Each person is unique and just as people differ in their fingerprints, they also have a unique and slightly different DNA sequence. Half of a person’s DNA is received from their mother, and half is received from the father. However, while fingerprints have no value for establishing family relationships, the minor variations in DNA sequence are extraordinarily useful for this purpose. All cells of our body contain DNA, skin cells from the lining of the cheek provide a simple and convenient source of material.

DNA is purified from these cells and the minor variations are read out as a type of bar-code by a machine. When the net DNA ‘barcodes’ from family members are lined up next to each other it becomes clear when a child is related to biological parents because half the stripes in the bar-code like signature will line up with those of the mother, and half will line up with those of the father. On the other hand, in the absence of a biological relationship, the DNA signatures from a child and from a potential parent are not found to have 50% in common. It may be appreciated that DNA testing is the most convenient and scientifically accurate method of determining relationships between people.

Following are the list of companies who qssist in DNA testing:

DNA testing companies

• 23andMe (admixture, adoption, deep ancestry, genealogy) (health and trait reports also available in some countries)
• 24 genetics (admixture, exome sequencing, health, paternity, pharmacogenetics, whole genome sequencing) A company catering for the Spanish market
• African Ancestry (deep ancestry)
• AfricanDNA (FTDNA affiliate) (admixture, deep ancestry, genealogy)
• AncestrybyDNA (admixture, deep ancestry)
• AncestryDNA, a subsidiary of Ancestry.com (admixture, adoption, genealogy)
• Atlas Biomed (deep ancestry, diet, health and traits, sport) A test catering for the Russian market
• BritainsDNA (formerly Ethnoancestry) (admixture, deep ancestry)
• Centrillion Biosciences (aka TribeCode) (admixture, deep ancestry)
• CymruDNAWales - see BritainsDNA
• Dante Labs (exome sequencing, health, whole genome sequencing) A test aimed at the European market
• DNA Ancestry and Family Origin (FTDNA affiliate in the Middle East) (admixture, adoption, deep ancestry, full mtDNA sequencing, genealogy)
• DNA Consultants (admixture, deep ancestry)
• DNA Tribes (admixture)
• DNA Worldwide (formerly a FTDNA partner. See also Living DNA)
• Ethnoancestry - see BritainsDNA
• Family Tree DNA (admixture, adoption, deep ancestry, full mtDNA sequencing, genealogy, Y chromosome sequencing)
• Full Genomes Corporation (whole genome sequencing, Y-chromosome sequencing)
• Gene by Gene - the parent company of Family Tree DNA which now incorporates the companies previously known as DNA Traits, DNA DTC and DNA Findings (research, health, exome sequencing, whole genome sequencing)
• Genebase (deep ancestry, genealogy)
• GenoTek (admixture, genealogy, diet and fitness, family planning, health, talents and sports) A company catering for the Russian market
• Genographic Project (admixture, deep ancestry)
• Genos Research Inc (DTC whole exome sequencing; consumer focused healthcare big data spin out from Complete Genomics; Note: no genetic genealogy focus or tools)
• Guardiome (admixture, whole genome sequencing and interpretation)
• Helix (exome sequencing) US supplier of the Genographic Project Geno 2.0 Next Generation test
• iGENEA (FTDNA affiliate) (admixture, deep ancestry, genealogy)
• IrelandsDNA - See BritainsDNA (formerly Ethnoancestry)
• MyDNA Global - a new name for BritainsDNA
• Living DNA (admixture, deep ancestry) See also DNA Worldwide
• MyHeritage DNA (admixture, genealogy)
• Oxford Ancestors (deep ancestry)
• Roots for Real (admixture, deep ancestry)
• ScotlandsDNA - (formerly Ethnoancestry) (admixture, deep ancestry)
• Sorenson Genomics (laboratory services)
• Sure Genomics (whole genome sequencing and interpretation)
• TribeCode See Centrillion Biosciences
• Veritas Genetics (whole genome sequencing and interpretation)
• Xcode (Diet and Fitness, Precision medicine, Genotyping, Sequencing, Interpretation)
• YorkshiresDNA - See BritainsDNA (formerly Ethnoancestry)
• WeGene (admixture, deep ancestry, health, sports, traits) A test tailored for the East Asian market
• YSEQ (custom Y-SNPs, Y-STRs, SNP panels, whole genome sequencing)