Hi Mithlesh.

Kudos for passing Class 12 with flying colours.

If you wish to become a Scientist - Genetics or Geneticist after studying Biotechnology, I would suggest you to go for a specialized subject rather than plain Biotechnology at Master's level as Biotechnology is an amalgamation of many bioscience subjects and covers a vast spectrum of sciences. You can pursue M. Sc. Genetics or Molecular Biology instead (though no compulsion as such).

After completing your Master's, you can appear for CSIR-NET and apply for relevant positions in CSIR organizations.CSIR - IGIB is one such organization. You can simultaneously do PhD in any area of Genetics. 

A PhD degree with a good amount of research experience will eventually lead you to become a Scientist or Geneticist.

All the best.