Húrin is of the line of Hador Lórindol (Goldenhead). He has golden hair. So does his daughter, Níniel.
On the other hand, his wife, Morwen, is of the House of Bëor, which has dark-coloured hair. So does Túrin. So, Túrin did not inherit his father's hair colour.
Elanor was golden-haired, while Sam and Rosie both had dark-coloured hair. So, Elanor did not inherit her father's (and mother's) hair colour.
I've been too nitpicky long enough, so the thread is yours.