calculating paternity index of single inconsitency in mutation with python

PYTHON PROGRAMMING CODE TO ASSERTAIN THESE:

person genotype

mother ab

child bc

alleged father de

X = P(man without C will contribute C)
X = P(contributed gene will mutate) * P(mutated gene will be a C)
m = observed rate of mutations/meiosis for the locus
P(mutated gene will be a C) ie. Frequency of C allele = C
X = C * m

For the numerator (X) Probability = 2ab x 2de x 0.5 x m x C

In order to explain this evidence the denominator
must calculate the probability that the paternal allele
is C and a random man would have a genotype
inconsistent with paternity at this locus
Y = P(paternal allele is C and random man has no C allele)
= P(paternal gene is C) * P(random man has no C allele)

P(paternal allele will be a C) ie. Frequency of C allele = C
P(random man has no C allele) = probability of exclusion

Y = C * A

For denominator (Y) Probability = 2ab x 2de x 0.5 x C x A

hence the final result should be:

PI = X/Y

PI = (2ab * 2de * 0.5 * C * m ) / (2ab * 2de * 0.5 * C * A)

PI = m/A
N:B where PI is Paternity Index