Personal genomics is finally here.

23andMe, the Google-backed startup that promises to let individuals search and share their personal genetic information, just unveiled its service on its Web site.

For $999, anyone can spit in a plastic tube the company will send you, then mail it back for a kind of shortcut scan of your genome. Technically, the company will use gene chips to determine which of roughly 600,000 single-letter DNA variants, technically known as single-nucleotide polymorphisms, or SNPs, an individual possesses.

Those SNPs make it possible to get a rough sense of exactly which gene mutations reside in your genome, and thus what sort of probabilistic fate — nothing is predetermined, although your genes may predispose you to certain diseases or behaviors — your genetic code might have in store for you. 23andMe will put your genetic information up on what it says will be an extremely secure Web site for you to explore for disease risk, genealogy or personal ancestry.

23andMe, of course, isn’t the only company dipping its toes into these waters. A few weeks ago, another Silicon Valley startup called Navigenics made a big splay by “launching” its own personal-genomics service via press release, even though the company won’t be actually offering genome scans until next year.

Navigenics is also determined to toe the ethical line and so will only offer customers carefully selected information about their genome and what it says about the risk of developing particular diseases, essentially turning a full-genome scan into a sort of glorified set of individual genetic tests. That service, by the way, is slated to cost $2,500 plus an annual subscription cost of $250 or so. 23andMe is already looking like a far more interesting option, particularly for “infovores” who crave as much information about themselves as possible.

Iceland-based DeCode Genetics also just launched a personal-genomics service it calls DeCodeMe.

23andMe’s new Web site is spare and clean, offering a concise explanation of the personal-genomics service:

The “Gene Journal” offers a number of tools designed to help you make sense of your genome scan, from an “odds calculator” that helps you determine what your individual genetic profile suggests about your risk of developing conditions such as heart disease or cancer.

A “marker effects” chart sums up what’s known about the effects of different genetic variants, which may increase your risk of disease or offer protection against it. The site is chock-full of scientific references, background information, FAQs and even perspectives from medical doctors on the significance of genetics and various conditions.

In addition to the Gene Journal, 23andMe also offers a “family inheritance” section that lets you trace genes through your family history and even lay your genome out against those of relatives who’ve also been genotyped by 23andMe.

An ancestry section shows you how genetically similar you are to people around the world and how to compare your ancestry with those of family, friends, and historical figures via maternal inheritance (technically, via mitochondrial DNA) and, soon, paternal inheritance (via markers on the male-only Y chromosome).

Best of all, at least for those curious enough and scientifically inclined, a “genome labs” section lets you browse through your genome via what appear to be straightforward and uncluttered graphical interfaces. You can see how similar your genome is to that of other individuals who have been scanned, either by comparing overall genomes or by simply focusing on particular inherited traits.

A “genome explorer” lets you browse through your chromosomes. It’s also possible to look up particular SNPs directly to see the current state of knowledge linking them to particular physical traits or disease risks.

All that looks nifty enough, although it’s difficult to get too deep into the site without actually getting genotyped and seeing exactly how those tools work. The information available to the casual browser is certainly intriguing, and it’s far more detailed than Navigenics offers. (The DeCodeMe site looks similarly detailed, although you have to go through a free registration to see it.)

If I get a chance to actually try out the service — assuming I’m ready to actually entrust one of these companies with my genetic information — I’ll let you know what it looks like from the inside.

On a purely business level, it’s not entirely clear how 23andMe intends to make money. Presumably the company will get into that during its scheduled Monday Webcast, and if not, I’ll do my best to get a better sense of the company’s business plan.

Two other things are particularly striking about 23andMe’s service. The first is the complete absence of any reference to genetic counseling. The company seems to believe that people are capable of looking squarely at their genomes and the associated risk information it embodies without the need for support services aimed at helping them understand the context of their particular genetic variations. That may be right or wrong, but it’s very interesting in light of the effort Navigenics and other genetic-testing services like DNAdirect are taking to ensure that people don’t freak out if their gene scan delivers bad news. (More precisely, the possibility of bad news — once again, genes aren’t destiny, although they clearly influence the likelihood of various diseases.)

Similarly, and significantly, 23andMe also claims that it’s not delivering medical advice or actual genetic testing. For instance, here’s the relevant part of the site’s disclaimer, which you have to click through during the sign-up process:

"23andMe’s service is not a test or kit designed to diagnose disease or medical conditions, and it is not intended to be medical advice. If you have concerns or questions about what you learn through 23andMe, you should contact your physician or other appropriate professional."

This is clearly 23andMe’s strategy for sidestepping FDA regulation of its service, and it strikes me as a fairly risky play. After all, 23andMe presumably offers you exactly the same information that existing, FDA-regulated genetic tests do (and then some, of course). On the other hand, it’s also entirely possible that a whole-genome SNP scan falls into a regulatory no man’s land, particularly if the company makes no attempt to market the service as medically useful. This will definitely be an area to watch.

Obviously, privacy and security will remain concerns for many people, although there’s no good way to gauge in advance how well 23andMe will protect genetic data. More concerning, perhaps, is the question of what happens if — or when — some of the company’s customers react badly to genomic bad news. Bioethicists have long feared that some people might commit suicide, get depressed, or experience other major problems if they get unwelcome news from genetic tests — thus the emphasis on genetic counseling at other testing services. If the worst does come to pass, the following paragraph in 23andMe’s disclaimer is unlikely to be much comfort.

"You may learn information about yourself that you do not anticipate. This information may evoke strong emotions and has the potential to alter your life and worldview. You may discover things about yourself that trouble you and that you may not have the ability to control or change (e.g., your father is not genetically your father, surprising facts related to your ancestry, or that someone with your genotype may have a higher than average chance of developing a specific condition or disease). These outcomes could have social, legal, or economic implications."

However these issues play out, it seems clear that the launch of these services represents our collective first step into our new genome-centric future. Good luck to us all.