Answer:
The blood type of my grandparents would provide information about my parents' genotypes.
Explanation:
o find out if my parents are heterozygous or homozygous the best option would be to ask my grandparents their blood type.
If my grandparents have AA or BB blood types, both of my parents would be homozygous, but if one of my grandparents is AB, or AO, or BO there is a probability that my parents are heterozygous. Lastly, if my grandparents are both heterozygous, there is a higher probability that my parents are heterozygous too.