Not read the whole thread but BenefitsQuestions has it right, right back at the start!
mentalfloss.com/article/65058/when-did-pink-become-girl-color
"When Did Pink Become a "Girl" Color?"
To some extent, the shift happened after WWII. “Rosie the Riveter traded in her factory blues for June Cleaver’s pink apron,” NPR said last year. “Femininity got wrapped in pink, and so did products—from shampoos to fancy fashion.”
Indeed, the ‘50s and ‘60s are full of pink moments, from the strawberry-colored Chanel suit Jackie Kennedy wore on the day JFK was assassinated to Marilyn Monroe’s hot pink strapless dress from Gentlemen Prefer Blondes.
But Jo B. Paoletti, historian and author of Pink and Blue: Telling the Girls From the Boys in America, believes the line was firmly drawn in the 1980s, when two things happened. First, it became more and more common for parents to find out the gender of their children while they were still in the womb. Excited moms and dads wanted to buy gender-specific items for their new little bundles of joy, and of course, retailers obliged.
The other main reason, Paoletti theorizes, is because mothers who grew up wearing gender-neutral clothes and playing with toys that appealed to both boys and girls wanted their daughters to be able to revel in pink, lace, long hair, and Barbies. Marketers and advertisers just made this choice seem natural.
When you look at the big picture, the “pink is for girls” trend is a fairly recent one. It may not be long before the controversial pink- and blue-tinted aisles at big box stores have been replaced by some other shade entirely. "
I do hope so!