I was not always so comfortable in my own genome. Before I spit into the vial, I called several major insurance companies to see if I was hurting my chances of getting coverage. They said no, but that is now, when almost no one has such information about their genetic make-up. In five years, if companies like 23andMe are at all successful, many more people presumably would. And isn’t an individual’s relative risk of disease precisely what insurance companies want to know?

Image The company 23andMe introducing its DNA testing service last month in San Diego. Participants took various tasting tests: wine. Credit... Monica Almeida/The New York Times

Last month, alone in a room at 23andMe’s headquarters in Mountain View, Calif., with my password for the first time, I wavered (genetic?) and walked down the hall to get lunch.

Once I looked at my results, I could never turn back. I had prepared for the worst of what I could learn this day. But what if something even worse came along tomorrow?

Some health care providers argue that the public is unprepared for such information and that it is irresponsible to provide it without an expert to help put it in context. And at times, as I worked up the courage to check on my risks of breast cancer and Alzheimer’s, I could see their point.

One of the companies that plans to market personal DNA information, Navigenics, intends to provide a phone consultation with a genetic counselor along with the results. Its service would cost $2,500 and would initially provide data on 20 health conditions.

DeCODE Genetics and 23andMe will offer referrals. Although what they can tell you is limited right now, all three companies are hoping that people will be drawn by the prospect of instant updates on what is expected to be a flood of new findings.

I knew I would never be able to pass up the chance to fill in more pieces of my genetic puzzle.

But I had decided not to submit my daughter’s DNA for testing — at least not yet — because I didn’t want to regard anything about her as predestined. If she wants to play the piano, who cares if she lacks perfect pitch? If she wants to run the 100-meter dash, who cares if she lacks the sprinting gene? And did I really want to know — did she really want to know someday — what genes she got from which parent and which grandparent?