I've heard about services like 23andme, which offer genetic testing to the general public. As a person who knows very little about genetics, I'm interested in the subject and would like to know what the modern "commercial grade" genotyping really does. What are the limitations of commercial-grade "genotyping"? From what I've been reading, they test DNA against ~100 different markers, but do not really sequence it.
If I understand correctly, if DNA is sequenced, genetic markers and genes can be identified in it, including the newly discovered ones. However, (if I understand correctly) if DNA is genotyped, the genotyping is a one shot operation which states if some genetics markers are present in the DNA. To test against newly discovered markers, it would have to be genotyped again, right?
Thank you for any clarifications!