Dagdamor
Well you suspected that they were vegans, and they probably were. Raising a child on a vegetarian, especially vegan diet can be dangerous and I don't recommend it at all. As turned out in this case, the body didn't receive enough of the necessary proteins and anything else it needed to develop. And especially at this stage, when the child's bones are undergoing ossification, you have to give them a well-balanced and nutritious diet.

Too many people out there think that being vegetarian or vegan just means cutting certain products out of their life, such as meat, milk, eggs, etc. and not having to find a replacement for what is being lost from your diet.

But imho, a bit like faith (but i dont want to start a discussion about this here), that isn't a thing for parents to decide: a parent hasn't got the right to "force" his/her child to grow up vegetarian or vegan since the start (even if vegetarian diet is on all sides more "healthy" than carnivore one), it must be a choice that matures inside each person with every passing day. They should, of course, not forbid it to the child either...

that of what Dagdamor talked about is just an example to the extreme of what could such a choice brign to, so i'm not taking it as a "thesis", but still i think man is born omnivore and that's the primal nature. Any forceful changes to this nature since birth is to be avoided, imho.

Miles
"When the child is old enough to give an answer, the parents should ask if he/she wants to eat meat"
I do not agree with you here, how can a child decide something on its own without any knowledge? A time must passed away before he or she can do it's choise. There must be a fixed age, which called also 'majority'

Miles
"I'd personally bet a child raised in a vegetarian family would resent the idea of eating an animal..."
And that's the thing. Who will guarantee that growing up in vegs-family the child will get absolutely clear and unbiassed opinion? Any parents influencing their people with their own principles no matter is it 'good' (vegetarian in our case) or 'bad' (meat-eating). In your case you was growned in family of meat-eaters as I can remember. And I can suppose that the major motive for you to become a veg was the constant contemplation of your relatives gulping down all that meats and other 'bad' products. If you would not have such a 'bad' example right before your eyes day by day who can say that you'll interested ever in vegetarianism? Sounds strange I know. But we are considering the case of naturally unbiassed person, the hypothetical case. In reality all is much tangled.
If you would be growned in the children's home I think you wouldn't have such opportunity to choice with its fixed menu (I don't know yet maybe in european children's homes there are special menu for vegs exists?)