Genome analysis is also a lossy process that chops the data up into tiny bits, like a newspaper sent through a shredder. We then piece together matching sequences in a sort of puzzle. It's often a relatively inaccurate solution. Then we try to do that again with a different copy of the newspaper sent through a different shredder. And again. A genome might be comprised of 10x reads, 30x reads, 100x reads, with more replications representing higher confidence.

There might be ten million people who have quoted Harry Potter at some point in their blogs or forum posts. There are only so many words in the books.