Well, as we'll see in just a moment, crossing over a lot allows us to produce sex cells. It allows us to produce gametes that carry genetic information that is slightly different than genetic information found inside our somatic cells. And that's exactly why I, for example, don't look exactly like either of my parents. And that's exactly why I have my own set of unique fingerprints. It's because crossing over allows those gametes to obtain genetic information that is unique to that specific sex cell. Now, in our discussion of crossing over, we're going to focus on a type of organism we call the fruit fly.