Image taken from Sarah Hoffman's website, who has a boy who loves pink.
It seems there are no definite facts that claim who owned pink or blue throughout the ages. I've found for Western culture the following:
Babies and children wore white for a long time, gender was not an important factor before the 1900's.
It wasn't until the 1920's that Western culture started assigning the colour pink (and blue) to an individual gender.
Pink was actually an appropriate boy colour, because it was seen as more masculine, being close to the colour red.
Blue was seen as a more dainty and delicate colour, so was appropriate for girls (also think Virgin Mary).
But rumors are, the two colors were used interchangeably until World War II.
During that time one of the cruder examples of the shift for pink as a more feminine colour was a pink triangle to identify homosexuals in Nazi prison camps.
After the war women stopped working and became housewives, encouraged to wear pink lipstick and own pink cars....a more rosie outlook to life and family after the war.
Barbie was born shortly after and, of course, pink was her colour of choice.
Pink became the colour for girls and blue as a color for boys.
And so here we are today.
Sometimes fashion allows men to wear pink (or salmon), boys have a dash of pink in their t-shirt design and baby boys will get mistakened for girls if they're anywhere near pink.
On the other hand, majority of girls seem to gravitate toward the colour pink and dad's won't allow their sons to don anything in the pink family.
This is all generally speaking, of course, because if you are reading this post, you already know that kids of any gender can like any colour they want... even pink.