A kitten will be considered a cat when it's nine months old. I once read that a cat was adolescent from about 10 to about 18 months of age... I guess that means s/he's an adult past 18 months of age.
Ethnically, Mexican Americans are a diverse population including Mexicans of Indigenous ancestry, Mexicans of European ancestry (mostly Spanish), and Mexicans of Middle Eastern stock (mainly Lebanese).
Are they Latino, absolutely not, Latino is a group of people from Latin America and it easily refers to the Mestizos or the mixed race of Latin America. Spaniards do speak a Latin language but are not Latinos because Spain is not located in Latin America, it is in Europe.