To figure out what the genotypes are of the parents, you have to look at their what?

Each parent carries a gene for green (y) and a gene for yellow (Y). Place one parent's genes along the top of the Punnett square and the other parent's genes along the left side. Copy the genes down the columns and across the rows. Each of the four squares now shows a possible genotype combination

I hope this helps

Explanation:

this is math not biology xd