Geralt's hair is white because he went through 2 rounds of mutations during the Trial of the Grasses instead of just 1. His body 'responded well' the first time so they subjected him to another which caused his hair to grow in white. Geralt was roughly 12 y/o when this happened.

And the Trial of the Grasses is ROUGH. Every 1 in 4 boys die from it.

The process involves being strapped down and being injected with mutations and poisonous concoctions that literally break down physical bodily matter so it can be reconstructed using magic. It's mentioned-

that at one point, Geralt was blind for a few days and in agonising pain from the poisons before his eyes were reconstructed and described it as one of the most terrifying experiences of his life.

He carries a lot of trauma from it and it is implied heavily that he -and many-

other Witchers (e.g. Lambert) - have PTSD over the process of the Grasses. In Witcher 3, you actually find 'Sad Albert' (the table boys are strapped to) at Kaer Morhen for a quest and Geralt is pained and uncomfortable to even look at it. The dialogue is really good there too-

you hear how tight Geralt's voice becomes and his sentences are more clipped than usual.

In the novels, Geralt's extra mutations are why he behaves a little more 'wolf-like', accounting for his sharpened teeth, how he bares them and growls at people, and his litheness in combat.

And that's your Witcher fact for today!

I guess I'm now a Witcher Facts twitter page on the side lmaooo

So many people ask why Geralt's hair is white when no other Witcher has it (besides Vesemir, but that's bc he's a grandpa in witcher terms lmao) so I thought I'd throw some Trial of the Grasses lore out there for y'all!