What is written FIRST in a genotype?

it depends on what traits they have, Dominant or recessive. On the punnet square, Capital letters ALWAYS come first(Dominant alleles/traits)

Explanation:

genotype = the genes of an organism; for one specific trait we use two letters to represent the genotype. A capital letter represents the dominant form of a gene (allele), and a lowercase letter is the abbreviation for the recessive form of the gene (allele).

i thinking chemical change