It can go either way. I was very careful with my first, to only let him eat wholefoods and healthy stuff. Tried (unsuccessfully) to wean him on pureed broccoli, as read it was better to do bitter veg first, for some reason. Followed all the health visitor advice. He ended up with such a complex about food he wouldn't eat ANYTHING, to the point he would get weak and lethargic. It was absolutely awful. Eventually we turned it around, and now I'm so grateful that he eats well - lots of wholegrain, fruit, veg, dairy... but also chocolate, sweets, crisps... he is three, tall, slim and very active.
The second we weaned on fruit and white breadsticks, and never had an issue with food (please God, let it stay the same!). He's one, and does have a small treat after lunch and dinner, along with getting all his healthy foods.
I guess my point is, you might be lucky and have a child who eats well, but with other children you can do all the "right" things, and still end up with major issues. It's a bit annoying when people undermine your efforts to feed your babies healthily, but ime if you make it into a big deal it can backfire. Or, it might not! They're all different, after all.