In the past year, several direct-to-consumer genetic tests have been introduced to capitalize on the falling cost of genomic technologies and the flood of studies linking genetic variants to disease. The tests generally use two technologies: microarray analysis, which searches the genome for specific genetic variations, such as single-nucleotide polymorphisms (SNPs), linked to disease or ancestral groups; and sequencing, which reads a DNA molecule letter by letter. Getting your genome examined is great fun. But the understanding of ancestry is still evolving. And broad genetic screening hasn’t been tested for its clinical utility.

Company: Genographic Project, Washington, DC

Cost: $99.95

Technology: Fragment analysis, SNP analysis, sequencing

What you get: Data on your haplo­group–ancestors with whom you share genetic features

What it’s good for: It can illuminate migratory paths taken by your ancient ancestors

Extras: Proceeds go to field research and a ­legacy fund supporting education and ­language-preservation initiatives in indige­nous communities

Company: DeCode, Reykjavik, Iceland; and 23andMe, Mountain View, CA

Cost: About $1,000

Technology: Microarrays that test for up to one million genetic variations

What you get: Information on ancestry, genetic risk of disease, and characteristics such as eye color

What it’s good for: The microarrays detect variations linked to disease and indicate varying amounts of risk; best for the cautious who want all information on the table

Extras: Both companies’ online interfaces let you compare your genome with those of family and friends; 23andMe’s also lets you compare your ancestry with that of notables including Bono and Genghis Khan

Company: Navigenics, Redwood Shores, CA

Cost: $2,500

Technology: Microarrays that test for up to one million genetic variations

What you get: Information on genetic predisposition to 18 diseases, including Alzheimer’s and type 2 diabetes

What it’s good for: Like the services from deCode and 23andMe, ­Navigenics’ tests indicate varying amounts of disease risk

Extras: This is the most medically oriented of the three micro­array analysis companies–and the only one that offers genetic counseling

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Company: DNA Direct, San Francisco, CA

Cost: $175- $3,456

Technology: (varies by test) Various, through subcontractors

What you get: Information on your risk for more than a dozen conditions having very well documented genetic components, such as cystic fibrosis and breast cancer

What it’s good for: Test results can inform preventive actions: someone found to have a mutation linked to breast cancer may choose prophylactic mastectomy, and prospective parents who both carry a cystic fibrosis mutation may screen their embryos

Extra: DNA Direct provides the most usable information for your personal-genomics dollar

Company: Knome, Cambridge, MA

Cost: $350,000

Technology: Sequencing

What you get: The sequence of your entire genome and an analysis by a team of scientists; customers get a personalized report tailored to their particular interests, which could pertain to health, ancestry, or physical traits

What it’s good for: Sequencing detects myriad genetic variations that can’t be identified with microarrays; if these variations are later linked to disease, customers could gain further insights

Extras: You’ll join a rarefied club whose members include genomics pioneers James Watson and Craig Venter–the first humans to have their genomes sequenced