Answer:
Yes, This can happen if both the parents are heterozygous.
Explanation:
To have a child with blood type O, both the parents should have at least one copy of allele "i". This is required since the genotype of a person with blood type O is "ii". Parents with blood type A and type B can have a child having blood type O. Here, the genotype of the parent with blood type A should by IAi which means that it is heterozygous in nature. Likewise, the parent with blood type B should have genotype IBi.
