Answer:
Two heterozygous parents have a 50% chance of contributing one of their alleles to each offspring.
Step-by-step explanation:
Individuals who are heterozygous for a specific trait have two different alleles in the gene that determines that trait. This characteristic makes their chances of contributing each of their alleles to the offspring 50%.
The alleles of a gene are distributed in the gametes by the process of meiosis, which results in daughter cells with half the genetic charge, so each gamete can only have one copy of the allelic pair of a gene.
On the other hand, if an individual has two equal alleles for a characteristic in a gene, he has a 100% chance of passing that allele on to his descendants.