Yes, Telchar is on the right track.
In Tolkien's genetics of the Elves, golden hair (which for personal reasons I see as a more reddish blonde than a whitish blonde) is a trait of the Fair Elves or Vanyar. Fingolfin like Finarfin was a child of Indis, Finwe's second wife, but he and his children were of the Noldorin look. Dark, raven hair with bright grey eyes. Turgon's daughter, Idril, was golden haired, but her mother was also a Vanya.
So, I'm not sure about Gil-Galad, but without some definite indication, I'd assume he looked like his father and grandfather, and did not pick up any recessive gene for hair color, because his mother was probably a Noldo, too. But who knows?
What's interesting about this is that physical heredity aside, Elros, Elrond and their children had less Noldorin in them than Vanyarin or Telerian. Maglor's foster-sons were as follows:
Maiar: 1/16
Vanyar: 5/32
Noldor: 3/32
Teleri: 5/16
1-Edain: 1/4
2-Edain: 1/16
3-Edain: 1/16.
Even Celebrian was 3/4 Teleri, 1/8 Nolder and 1/8 Vanyar.
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"Manwe keep you under the One, and send fair wind to your sails."
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The hoes unrecked in the fields were flung, __ and fallen ladders in the long grass lay __ of the lush orchards; every tree there turned __ its tangled head and eyed them secretly, __ and the ears listened of the nodding grasses; __ though noontide glowed on land and leaf, __ their limbs were chilled.
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