I was about to agree with this because I have an 11 year old boy who is nothing like Nicholas, which is partly my reason for finding Nicholas improbably perfect. But it then occurred to me that Nicholas is far more like my daughter was when she was 11. People have commented that Nicholas is essentially Nicola in a Tudor boy's dress and I can't help agreeing because Nicholas does seem far more like a girl.
(Reading on, he doesn't seem to change much either between the ages of 11 and 16; and he certainly never acts like a teenage boy, but that is a discussion for a future thread.)