that using color for baby gender identification is (perhaps) a pretty recent development. Earlier in the twentieth century, color identification was used but it was reversed. That is, pink was used for boys and blue for girls. This was noted in several newspaper articles (1914, 1918) advising that since pink was the stronger color and better for boys whereas blue is more delicate and therefore more suitable for girls.
It is also stated that the current identification didn’t become uniform until the 1950s. Nazi Germany made homosexuals wear a pink marking and this may have had something to do with the switch in gender identification color.
But it is also said that blue may be associated with boys because having a boy baby was considered associated with good luck in ancient times. So the boy baby was dressed in blue since that was the color of the sky where the gods lived and was considered a way of warding off bad luck. Same thing in Greece where blue eyes were considered to be able to turn away evil.
In ancient China, red dye was relatively cheap and plentiful whereas blue dye was much more expensive and rare. So it was considered appropriate to dress a son in blue because he would bring a dowry to the family when he married.
Bookmarks