Hehe I had to watch that sequence several times before I could figure out what he'd said. I love Sherlock's response "And there's an entire childhood in a nutshell"

Yes but in English 'Queen' has a double-meaning. But Mycroft practically is the British Government.

Just trying to let one of our new German members know that the word 'Queen' has a double-entendre. You know, like Queensland! Lol

Only by...a royal mile! Lol

That Mycroft was always acting like a parent towards Sherlock, telling him what to do, trying to boss him about etc. Maybe?

This is turning into quite an interesting thread...
A few months ago, I wrote a somewhat longish post on how Sherlock is the typical younger brother (see Character analysis thread "Sherlock's relationship with Mycroft").

There is of course a counterpart to that - Mycroft, the typical older/oldest sibling. Let's have a closer look...
As the Doctor said, he will do anything in his power to try and protect and guide young Sherlock. He literally feels like a second mother. He cannot help himself, he cannot possibly understand that his brother could cope without him, or that he needs to make his own mistakes.
This scene is the perfect example: Mycroft does not ask, as other people might, "Shall I be mother?" - No, he immediately assumes the role, taking it absolutely for granted that nobody else will.
It does not even occur to him that his behaviour might come across as patronizing, or as Davina has put it, bossing others around.

Do you think Sherlock's reaction has something to do with Mycroft's choice of words? I suppose he could have expressed it in a different way without using the word "mother". Of course we know nothing about their parents. Just an idea. 

Exactly. I smell some domestic problems there.

I heard that on one of the commentaries Benedict says that Sherlock found out that his father was having an affair. I'm thinking maybe a young sherlock told his mother this causing his parents to spilt up and his mother to withdraw leaving microft to raise him. Thoughts?

It's interesting that Mycroft and Sherlock are talking to each other as brothers when they are alone and nobody's around, so they haven't to prove anything.

I have been won over by Moftis and Gatiss' Mycroft interpretation, and am a big fan of those small moments where we see the brothers among themselves.

E.g., Sherlock looking to his older brother for guidance outside the mortuary on Christmas day..