The amount of alleles that a baby Guinea pig inherit from the mother are two , 1 from its mother and 1 from its father ( The very reason why we use them as an experiment tester is because this similarities)
For Example, if its mother hat a dominant black fur (BB) and its father has recessive grey fur (bb) , there is 100% chance that the baby will has a Bb genotype, which will give them either black fur or dark grey fur.
