Microarray vs Whole Genome Testing

DNA in Genealogy Research

Living DNA in Genealogy Research

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Ethics and DNA Testing

Often when people purchase a DNA test they assume that all of their DNA has been tested. This is usually not true. Microarray DNA testing is what is done by Ancestry, 23andme, MyHeritage, FamilyTreeDNA, and Living DNA. With this method, the company individually selects 500,000-800,000 SNPs and only tests those. Although this is less than 1% of the base pairs that you have in your DNA, the SNP's are carefully selected and spread across the entire genome. It is accurate enough to identify your genetic relatives in the database as well as predict your traits and ethnicity.

Whole genome testing is much more expensive because it tests every base pair (approximately 3 billion). The disadvantage is the vast majority of base pairs are identical in every human who as ever lived or will ever live and are thus not particularly useful for genetic genealogy. The advantage to whole genome is it can test for rare mutations that would not be tested for otherwise. Whole genome testing can even distinguish the DNA of twins as one may have a novel mutation that the other does not. In rare cases it may be neccessary to use whole genome testing to determine which of two twins is a biological parent to an adoptee.