To Separate Or Not To Separate, That Is The Question...

    Why is it automatically assumed that you will / want to separate school aged twins?  I believe that it is thought that by not separating them you will cause them psychological damage.  What if people compare them?  What about their individuality?  Blah, Blah, Blah.  It is obvious to me that the creators of these "absolutes", were not twins, nor did they have twins.
     The topic of separating Riley and Rowan has come up a few times.  When I first enrolled them for junior kindergarden I was asked if I wanted them together or separated.  I was told that they like to separate them in grade three.  At that point I wanted them together because it would allow them a better school experience if I kept them together.  All of my children are painfully shy.  When they were little Rowan had terrible separation anxiety.  Keeping them together allowed them to be placed with their "best friend".  On their first day of school I left them, and looked back through tear filled eyes.  When I looked back, they were sitting together holding hands.  They gave each other comfort.  Comfort made them love school.
    As time has progressed their shyness has subsided a bit.  They are now very comfortable going to school.  They don't "need" to be together, but it's easier for me.  We have a small school.  There are generally two teachers for each grade.  Over the coarse of having older children I have gotten to know all of the teachers.  I know what teacher works best with my children.  When I can, I request a teacher for my children.  My kids learn their best when they feel secure and cared for.  They do not do well in chaos, nor do they do well with teachers that use harsh words, or overly yell.  Some kids need teachers like that, mine don't function well in that atmosphere.  Why would I separate them just for the sake of separating them?
    Why do they like to separate them in grade three?  I come back to why would you arbitrarily separate them?  I could understand separating if they were too reliant on each other.  I could understand separating them if they were too disruptive together.  Riley and Rowan don't look like siblings, Riley looks like a little cloned me, and Rowan looks like a little cloned Christopher with red hair.  They act as completely separate individuals.  They don't even talk to each other in class.  They have different friends.  They are complete individuals.  They are absolutely nothing alike in their personalities.  Their gym teacher was new to our school this year, and did not even know that they were twins.  She saw that they had the same last name and assumed that they were cousins.
    Last week I had a meeting at the school with our principal and vice-principal.  We were discussing what will happen next year, grade three.  It was a foregone conclusion that we would separate them.  They were both taken a little aback when I told them I wanted them together.  I explained to them that I like to request teachers that my children will thrive under, and keeping them together makes my life that much easier, and with four kids, life needs to be made as easy as possible.  I could see the understanding beginning to form on their faces.
    I come back to my question, why would you arbitrarily separate twins?  Should you not look at the individuals and then decide?  Let me know what you think.