I did the 23andme thing a few years ago. I browsed the risk factors, but most were of the form "there's a 40% chance that your gene gives you a 6% chance of thus-and-such. My risk of Alzheimers is slightly elevated above the average. My risk of something else is slightly less than the average. And so on and so forth. They correctly predicted that I do not like cilantro. Apparently there's a single gene for that.
But I did the test because I was curious about my ethnic background. My grandfather insisted that in spite of a thousand years of the diaspora in Eastern Europe, we were 100% Jewish. That seemed unlikely to me, given that the Jews of the Middle east are much darker-skinned than we are. Turns out I am 94% Ashkenazi. I'm 3% Neanderthal (twice the average). And a couple of percent mixed European. According to Wikipedia, the Ashkenazi line was probably formed from a relatively small population of Middle Eastern men who went to what is now Italy and took European wives, and after that there was very little mixing with the locals. So my grandfather was right that we are nearly 100% Ashkenazi, but I was right also because Ashkenazi has a large European component, and wrong because apparently, for the next thousand years, there was not much mixing.
I'm not sure what good it would do me to know that I have a 6% greater chance of getting this, and a 4% lowered chance of getting that.
Occasionally I get emails from 23andme asking me to take an on-line survey, which I do. Then a bot thanks me for helping research. I think I might balk at getting a spinal tap. That just sounds really scary. I have a very low pain tolerance.