This is an old article but I thought was quite good http://www.theage.com.au/articles/20...569786596.html

One bit that stood out in relation to the above

"However, she says it's ``too simple'' to say that a younger child will not cope as well as an older one, or that it's better for boys to wait a year, adding: ``If we expect boys to be behind, we tend to treat them that way and that is how they turn out.''