So my children are 1/8th Hispanic. Their great-grandmother was a Chilean born to Spanish parents. Her brother taught his four children Spanish and took them to live in Chile for half of each year. These cousins have Spanish surnames, are fluent, and hold positions in universities and governments that are Latin American or Hispanic in nature. Great-Grandmother's four children raised THEIR children in the South, gave them their father's very banal surname, and did not teach them Spanish.
My children, blonde like their Swedish great-grandmother and her descendents (they are 1/16th Swedish too, I guess?), do not look Hispanic, nor are their names latino/a, though my daughter is named after the Chilean great-grandmother - just an American pronunciation of the name. They reluctantly take Spanish as a special in school, and grumble at my attempts to teach them conversational Spanish.
I am about to fill out a public school form asking us if our child is of Latin American descent. I am about to fill out a Census form that asks if my husband is Hispanic. He's actually 1/4th!