‘A very small sample of tissue or even a drop of blood can help determine paternity’

‘A very small sample of tissue or even a drop of blood can help determine paternity’. Provide a scientific explanation to substantiate the statement.
or
There is a paternity dispute for a child. Which technique can solve the problem? Discuss the principal involved.

DNA fingerprinting is the technique used in solving the paternity dispute for a child. DNA fingerprinting involves determining nucleotide sequences of certain areas of DNA which are unique to each individual.
The DNA sample can be taken from a very small tissue- or even a drop of blood can be used. The basis of DNA fingerprinting is DNA polymorphism.