The golden-haired tendency of the Rohirrim could indeed be explained by a connection with the House of Hador, but at further removes from Tuor specifically.
The Northmen of Rhovanion eventually became the Rohirrim, and of them it is said:
Quote:
[They] were descendants of the same race of Men as those who in the First Age passed into the West of Middle-earth and became the Allies of the Eldar in their wars with Morgoth.
|
Unfinished Tales Cirion and Eorl
Footnote Four adds:
Quote:
The Northmen appear to have been most nearly akin to the third and greatest of the peoples of the Elf-friends, ruled by the House of Hador.
|
The genetics for blonde hair were simply present in both some of the Edain who went into Beleriand and their kin who remained behind.