It actually wasn’t until the 1940s that the colors became set in stone
Pink is for girls. Blue is for boys. Of course our society allows exceptions now and again, but imagine showing up to a boy’s baby shower with a pink bib and matching pink shoes. There would be whispers that either you’re nuts or you must not have seen the ultrasound on Facebook.
But things weren’t always this way. Jo B. Paoletti, historian and author of Pink and Blue: Telling the Girls From the Boys, has found that pink and blue designations are extremely recent phenomena. Around the turn of the century, both sexes wore easily bleached white dresses up to age 6, meaning that gender neutral clothing was the norm. Then things slowly shifted. From a superb piece over at Smithsonian (that you should read in full!):
For the rest of the story: http://www.fastcodesign.com/1672751/how-pink-and-blue-became-gender-specific