My dad has thick, dark brown, wavy hair, but it's never long enough to tell HOW wavy it is... But I guess it's like mine, 2c. My grandpa and gran-grandpa also has/had wavy hair.
My mum's hair is very dark blond/light brown, a bit thinner than mine and only a bit wavy, 2a I would guess.
And my own hair: it's blonde, pretty thick and a 2c curl pattern with some 3a ringers