Blue, Pink, and Yellow (And Rubber Bands)

I was just looking at my foot, and I felt something odd on my sock. It was a rubber band. It is, however, a mystery as to how it got there. In my mind, there are two options. One; I stepped on it. I don't feel that this is true, as the rubber band is practically glued to the sock. Two; DD tried to wash the pair of socks, and had a mishap somewhere along the line. Yep, I have a huge feeling that is the correct one.
Just recently I came into the kitchen (location of washer, dryer, and fridge), and he was there, trying to open a large bottle. The door of the washer was open, and I understood he was about to start a wash. "I can't get the soap open!" he said, frantically twisting the cap. Just as he looked down and read "apply pressure and twist clockwise," and was about to open the bottle and pour it in, I realised the awful truth. "Stop, that's bleach!" I yelled. Luckily he did stop, and the clothes were saved. He insists, and I am prone to agree, that he is just not cut out for housework.
This led us to another discussion about what exactly 'cut out for' means. I am of the mindset that it has something to do with paper dolls. DD said, "If you cut out a fireman, you can't expect him to be good at housework, can you? Only fighting fires."
I am personally fascinated with the origins of expressions, idioms, phrases and some words.
Threshold, for instance, has its roots in the fifteen hundreds, when floors were covered in thresh(straw). This was cleaned out every so often, and had the bonus of soaking up spills of all sorts. Anyway, what with people walking in and out, the thresh tended to gravitate toward the doorway, and fall outside. What to do? Well, put up a board across the door at floor level to keep the thresh in, effectively, a "threshold".
Now to today's REAL topic; baby clothes. They are blue for a boy, pink for a girl, and yellow for a we-don't know-yet or a we-aren't-telling. But what about all the other colours? There are so many. I noticed this when my aunt asked MM and I to buy some ribbon for a baby blanket she was making. They had the cutest one that said "tiny hands, tiny feet" with little pictures of little footprints and hands all along. Well they only had it in three colours: blue, yellow, and pink. Why? What about tomboys? What about boys who like pink, and girls who like blue? And how would you like it if your baby blanket was yellow? Oh, well they didn't even know what sex I was, or they wanted to stay 'neutral' when choosing clothes for me.
Then I thought maybe it's so people can tell what the baby is. Sometimes it's hard right away. So people who see a pink blanket know it's a girl, and people who see a blue blanket know it's a boy, and people who see a yellow blanket ask. And if you have twins, you can tell them apart by their blankets. So maybe it is a good thing. However, one has to ask, why baby blue? What about baby pink and baby yellow?