Book on puberty that covers both sexes?

[KBwan]

Can anyone recommend a book for pre-teens that covers body changes and a bit of gentle sex (!) education for both boys and girls?
It confuses me no end that publishers seem to think it's OK to make 50% of the population 'a mystery' from such a young age by splitting so many puberty books into girls and boys... I have a mix of DCs and want them to understand what the others are going through too!

[Sadik]

The "Lets Talk About" series by Robie Harris are excellent. For an older pre-teen (say from school year 6 upwards), "Lets Talk about Sex" might be right, otherwise one of the slightly younger pitched books.