In molecular biology, restriction fragment length polymorphism, orRFLP, is a technique that exploits variations in homologous DNA sequences. It refers to a differencebetween samples of homologous DNAmolecules from differing locations ofrestriction enzyme sites, and to a related laboratory technique by which these segments can be illustrated. InRFLP analysis, the DNA sample is broken into pieces and (digested) byrestriction enzymes and the resultingrestriction fragments are separated according to their lengths by gel electrophoresis. Although now largely obsolete due to the rise of inexpensive DNA sequencing technologies, RFLP analysis was the first DNA profilingtechnique inexpensive enough to see widespread application. RFLP analysis was an important tool in genome mapping, localization of genes forgenetic disorders, determination of riskfor disease, and paternity testing.
Hope it helps..
        
             
        
        
        
Answer:
not 100% sure but
Explanation:
might be because each fruit fly has a different eye color because offspring from parents will have different eye color. or it might be from some sort of mutation that happened, that might be why they still have the gene to orange eyes. or red eyed fruit flys(or fly) migrated into a orange eyed populating and had offspring like that, that would also explain why red eyed fruit flys have the orange eyed gene. 
again not 100% sure
but I hoped it helped a little
 
        
             
        
        
        
False, it will probably last around 50 more years