We're mixed race in my family, as are a lot of Caribbean folk (due to the native Caribe islander "Indians"--Asiatic if one is to classify by race categories--the Africans brought over due to the heinous slave trade , and the Europeans who came over, so all three artificial racial constructs are represented).
We have all three--from "Indian", Afro-Cuban, and Spanish. Mom, whose dad was blue-eyed and very Spanish in looks and who herself was proud of the native Cuban Indian blood in her background, liked men of a certain look, as first husband and my dad (second husband) looked a lot alike (biracial men with dark hair, dark eyes, darkish skin, wiry frame). But none of us four kids have similar hair.
~~Eldest sis (first husband's only child with mom) has 3c/4a, coarse, dry, black, grows long easily, but is quite prone to kinking.
~~Older brother has Indian hair--straight, thick,black. Not a wave in sight. Never have seen it with frizz. Ever. Lays smooth. I wanted that hair so bad.
~~Middle sis: fine, soft, slightly wavy brown with natural highlights of red and blonde (she was a blond child). Ironically, she is always trying to get curls, while I, the ubercurly girl, was often trying to smooth mine out. I envied her hair growing up, as it doesn't frizz like mine.
~~Me: 3b, almost black, very dry, medium, prone to frizz, but easily styled, so relatively versatile. I can curl it or straighten it with ease. But the dryness got worse with age due to hypothyroidism, and it got curlier, too. Me, as a baby: curly; me as a kid, straightish hair that didn't hold a curl too long; twenties, wavy-curly; thirties on, really curly. Weird.
Mom had straight hair she was always perming. Dad had fine but plentiful curly-wavy hair, very soft, not dry.
It's so odd to me we have such different hair.
but as we're all multi-racial, I guess the gene pool causes diversity in features and hair (we do not look like each other, though we can see either mom's this or dad's that in each other).
I did grow up with a lot of Puerto Rican friends (they often had hair like me) and Irish kids (Catholic School), and lots of curlies among the Irish studients I went to school with, and ditto the priest and nuns. I think some interesting raiders visited ye Emerald shores....