What fraction of the offspring resulting from a heterozygous by heterozygous dihybrid cross are homozygous recessive for both traits?

In a dihybrid cross between two heterozygous parents (AaBb x AaBb), the probability of producing homozygous recessive offspring for both traits (aabb) is 1/16. This is derived from the Punnett square, where the combinations of alleles reveal that out of 16 possible offspring, only one combination results in homozygous recessive for both traits. Thus, the fraction of homozygous recessive offspring is 1/16.