Is 'Pink = Girly' a Myth?
priceonomics.com
priceonomics.com
Some claim this is because they do not want the bridesmaids to outshine the bride. Others say it is because they need a design that works well for a group that may consist of people with different skin tones, sizes, and shapes, and that is not too expensive for the bridesmaids to buy, and this limits choices. Whatever the reason, it seems that a lot of these dresses are ones that the bridesmaids would not be choosing if they got to pick their own dresses.
That said, yes, pink = girls, blue = boys is a fairly modern convention. This was covered on the "Adam Ruins Summer Fun" episode of the excellent new show "Adam Ruins Everything" on TruTV [1].
Here is the reference cited on that episode for their discussion of boy/girl blue/pink [2].
[1] https://en.wikipedia.org/wiki/Adam_Ruins_Everything
[2] http://www.smithsonianmag.com/arts-culture/when-did-girls-st...