Dr Robin Cotton discusses how each of the 46 chromosomes are different

Robin:
Well, okay, let's suppose we took all 46 chromosomes and we laid them out on the table, and they'd look like little "x's". And if we were able to do that what we could find is that on all of those chromosomes there were little pieces that weren't the same. The pieces that aren't the same are sprinkled around in the DNA, they're not all in one place.