And it makes perfect sense. No discerning female reader wants short and fair, with an ugly mug. God knows, she probably lives with one (throw in a beer gut for good measure)!
But back to hair colour - from what I've read, a blond hero doesn't figure in the genre.
His hair has to be thick, jet black or dark brown (maybe the tips can be sun-kissed, but never bottled!) and there has to be lots of it. There's no such thing as a hunk with a comb-over on the Greek archipelago.
Romance-novel covers are a good indicator of hair-colour preference - no blonds feature, even when we're talking Sweet or Medical.
The book titles also say a lot - you won't find any golden follicles on the noggin of a bloke in The Spanish Doctor's Love Child or The Greek Tycoon's Blackmailed Mistress.
Even historically, blonds have never fared well. They are usually portrayed as weak and/or villainous.
In film, blond actors tend to play the baddies (eg: nasty Germanic types in the Die Hard films and Paul Bettany as an albino monk in the Da Vinci Code) or hapless himbos (Owen Wilson = endearing). They're just not sexy enough.
So, to all the cute Magic-Silver-White surfie types and gorgeous Nordic gods I have ever loved -
When it comes to romance writing, you just don't make the cut.
(The photo is of dark-haired - do I detect golden tips? - American actor Dylan McDermott. He'd make the perfect playboy prince/recalcitrant billionaire rancher/moody genius surgeon - take your pick to fit the pic)