Even with historical fiction it is the same. Human behaviour has not changed over the years. This is what is so astonishing. The overlay of fashion, speech, social mores and life style maybe, but read Georgina, the Duchess of Devonshire and you will find beneath the 18th century facade, a very modern woman. Read Anna Karenina and you will find her heartbreak and problems are universal. Read about the intrigue and double-dealing in Tudor England and you could be in a John Le Carre spy novel. Human nature remains unchanged, no matter what century you are in.
If you want to write historical fiction get your background 100% correct and then create your characters.