I think it's all about passion for languages. I have bilingual children and my first was having difficulties with my native language compared to the second one. It's all individual...So the answer is 

> it depends

in my opinion I think there is no advantage over the children from monolingual. Children from bilingual families take 2 different languages as one. So in some sense there are still monolingual... 

here is some paper:

> Because a key expectation parents have is for their child to perform
> well in school, it is important for parents to know that bilingual
> children and monolingual children develop their learning abilities at
> different speeds. Children learning two languages learn each language
> more slowly than monolingual children learn their native languages. It
> is easy to understand why -- children have a limited amount of time
> with which to dedicate to listening and reading language; if a child
> is bilingual, he will split that time between the two languages, which
> slows his learning speed. This often affects the academic performance
> and communication skills of bilingual children, which can cause stress
> in the family. In a sense, the average school is set up to go at a
> monolingual speed, which might outpace bilingual children.

http://everydaylife.globalpost.com/child-development-bilingual-vs-monolingual-household-7371.html

> Bilingual 12-year-olds perform worse at school than their monolingual
> peers, a researcher at Sweden's Örebro University has found.

http://www.thelocal.se/20110323/32766