Do alleles of a gene necessarily be able to originate

Question: Do alleles of a gene necessarily be able to originate
- Keywords:
  alleles
Asked by abtb355 to Cheryl on 21 Jan 2017.
- Cheryl Andisi answered on 21 Jan 2017:
  
  @abtb355,
  I am not sure I understand what your question means. could you please rephrase ?
  Alleles are different versions of the same gene that are located on the same spot on sister chromatids on a chromosome. Eg the alleles coding for height -tall and short, or eye colour.
  Please rephrase and lets discuss more

Question: Do alleles of a gene necessarily be able to originate