Genetic testing or DNA testing which provides information about the chromosomes or genes or proteins 

Step 1 :- Once a person decides to proceed with genetic testing, a medical geneticist, genetic counselor, primary care doctor, or specialist can order the test after obtaining informed consent.
Step 2 :Genetic tests are performed on a sample of blood, hair, skin,amniotic fluid or other tissue
Step 3 :- After the scientists get the required details for the test, they perform the test and give the concerned person the report (of who is the father).

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Yours, Jahnavi