IMHO At ages 8-12 Kids get choices made
FOR them by responsible parents. They are too young to know the reasons for their choices or the nutrition required. As OP said the chid would thrive on starch alone left to own devices...
Now I'd be so careful to be very scared of soya and here's why. Not Fermented soya...but Unfermented soya
http://articles.mercola.com/sites/articles/archive/2010/09/18/soy-can-damage-your-health.aspx
Yeah, about that... remember where I mentioned above that you need to read a little deeper? The whole fermented vs unfermented myth has been debunked. It's a pity that it takes time to rid the media of all the hype articles published after a "Shocking Revelation" is made in a book that's released. Dr. Kaayla Daniel referenced in that article, that wrote the book "The Whole Soy Story" (which that whole article is based on) is a board member for the Westin A Price foundation... whose stated goal is:
“to disseminate the research of nutrition pioneer Dr. Weston Price....Dr. Price's research demonstrated that humans achieve perfect physical form and perfect health generation after generation only when they consume nutrient-dense whole foods and the vital fat-soluble activators found exclusively in animal fats.”
In fact most of the anti-soy hype is generated from people affiliated with that one organisation. The foundation spends a bucket load of money trying to undermine vegetarian / vegan foods, and soy in particular.
Here's a review of the book the author wrote called "The whole soy story":
http://eatkind.net/wholesoystory.htm
It shows just how badly the facts were twisted.
Here are some articles debunking much of the material linked above:
http://www.huffingtonpost.com/neal-barnard-md/settling-the-soy-controve_b_453966.html
http://www.huffingtonpost.com/neal-barnard-md/settling-the-soy-controve_b_453966.html
http://paretoraw.wordpress.com/2009/06/13/soy-controversy-debunking-the-myth/
Soy milk is quite safe and in fact the phytoestrogens found in soy milk help prevent some cancers because they are similar in structure to Human estrogen (so they bond to cells in the same way, blocking some estrogen), but they are chemically different, meaning they don't do what estrogen does. Are all soy products safe? Well I consider any processed food rubbish, so no I don't think processed soy food is ideal. But that's something I consider to be a problem with all processed food, not soy in particular. Whole foods are a must. On the GM note, I buy non-GM soy milk (Good Hope soy milk, bottled here in Cape Town).
We can go on all day about this, but the thread will likely get a little derailed. All I can say is that a little more digging is required before reading a seemingly tragic headline and shouting "OMG, we're all gonna die!".