The allele symbols on the outside of the punnett square represent the alleles in the gametes . Because when we done cross we got the gametes only . Example AABB X aabb , then we got the gametes AB and ab . This represent AB and ab are the alles of the gamete only . A allele is the alternative form of gene , if one is dominant other one is recessive.
So: both parents' genotypes (concerning baldness gene) are the same: Bb. Possible genotypes of an offspring: BB, Bb, Bb, bb . bb means non-bald girl or boy. Bb means bald boy or non-bald girl. BB means bald boy or girl. there is 25% chance of conceiving a child with a genotype BB. But there is also 50% chance of conceiving a girl. So the answer is: 25% x 50% = 12,5%
