I think pulling articles from the daily fail does not infact prove a point.
Someone mentioned elder siblings having a higher IQ, possibly statistically but not in every case. I said before I'm one of three, the middle child, with double the qualifications of my two siblings combined. Statistics are very easily manipulated to fit an argument
As for little emperor syndrome I'm reluctant to believe that is down to being an only child rather than parenting style.
For what it's worth my DD (almost 10) has been praised since she started nursery at 1 of have a very high EQ, she is hugely empathetic, a bit of a mother hen and children of all ages radiate towards her. She may not have to share a with a sibling but she is kind and would give anyone anything to make them happy. She has had to share me with my job and my studies. She may not have to share me with a sibling but she understands the importance of Mummy putting herself first too. She was brought up to understand that mummy deserves hobbies and weekends away to re-charge.
She is the favourite visitor for all the family, she is the best fun to the cousins, she holds a very interesting conversation with the adults, everything from the environment to politics to travel.
I think not having an 'annoying' sibling at home makes her more patient too.
Of course I only have my experience of her to go on. The only thing that sticks out as an 'only child' thing is the fact that she doesn't like being in places that are too noisy or crowded.
I truly struck gold with her, I'd hate to jinx my good fate by having to start over with parenting and end up with a child that is hard work and ill tempered. I have plenty of mum friends that love child 2 but were shocked at how much hard work they are and ultimately regret it.