In doing paternity testing the genetic tests are selected so that
(1) many tests are performed
(2) multiple loci are tested
(3) ideally on different chromosomes
probability of paternity =
= ((prior probability of paternity) * PRODUCT(all paternity indices)) / (((prior probability of paternity) * PRODUCT(all paternity indices)) + (1 - (prior probability of paternity)))
where:
• The product of all the paternity indices helps determine the conditional probability for the alleged father.
In testing for paternity, the prior probability for being the father is set at 0.5, which is intended to be a neutral starting point.
probability of paternity =
= (0.5 * PRODUCT(all paternity indices)) / ((0.5 * PRODUCT(all paternity indices)) + 0.5)