Hi C. -
Echoing everyone else's response to this post, KUDOS to you on your efforts to keep your kids' diets healthy.
Having been raised in the Philippines, I can tell you firsthand what soda drinking does to kids' teeth...it rots them out. Most children who live there have metal lining whatever baby teeth they have left...it should also be noted that letting babies stay on the bottle too long also results in rotten teeth - a practice many native Filipinos allow until way past five years old.
In any case, while I cannot understand how educated mothers today can let their kids drink soda and eat junk food, it does happen on a large scale (no pun intended), since most American children today are obese. I bet that most parents just give into the junk food temptation to pacify their kids and to buy themselves some temporary peace and quiet (at least while their kids are eating the junk). Coming down from a sugar rush is NO picnic for parents or for kids.
Because I'm half Filipino, I was raised to love all sorts of veggies, especially the more exotic variety like bok choy, napa cabbage, bitter melon, mongo beans, etc. I've raised my kids in the same way, and now they LOVE to eat these veggies and have very eclectic palets. They never shy away from new food, and always at least give things a try before saying "NO" to it. For kids, that's all we can expect. I've never had a problem with my kids being picky eaters, and I'm VERY grateful for that. Because they spent time in Hawaii, my kids also love sushi, which by the way doesn't mean "raw fish" - it just means vinegared rice. They mostly eat the California roll variety although my 4 four-year old son craves spicy tuna from time to time.
Since I have family members who've raised their kids on junk food, I don't make them feel bad about it. Instead, I just try to offer my support as much as possible. I pity them because they'll have a long, uphill battle of getting their kids to eat healthy.
C., you mentioned a possible connection between kids eating healthy and having good behavior...that's a very solid observation although I think there are definitely some cultural elements that contribute to behavior. For example, when we were living in Hawaii, my son was literally the only half-white, half-Asian child in his entire school of 96 kids. Every other kid was some Asian mix...Chinese, Japanese, Filipino, Korean, Vietnamese, Thai, Laotian, etc. I noticed right away that these kids were not only well-behaved, but extremely quiet and unwilling to take their initiative to lead their classmates in class exercises and/or projects. They were mostly very timid, but definitely well-behaved as defined by their teachers because they were raised to speak only when spoken to, a very common Asian practice. By comparison, my son seemed like a typical loud-mouth American kid because he dared to ask questions and took the initiative to lead play groups and also to clean up around the class. I wouldn't have it any other way. He's a thinker, a talker, a leader, and a DOER...as he gets older, he's learning to respect authority more without being a sheep. Whether that can be attributed to his healthy eating habits, I don't know. His doctor predicts that he will grow to a max. height of somewhere between 6'4 and 6'6, so he'll have a healthy-sized appetite in any case. It's our job as parents to make sure that he's set on the right path.
One thing I'd like to add to your thought is that in addition to not feeding my kids junk, I refuse to buy my kids ANY video game systems and games. My nephews started playing these games at a very young age, and while they're very bright and have great logic and reasoning skills as well as solid eye/hand coordination, the downside is that's ALL they ever want to do. They have poor conversation and socialization skills, and I think that's a shame. My kids are way too young to even care about this sacrifice, but when they're old enough, if they want to play these games, they'll have to go to their friends' homes. At least I'll be able to manage how often they play games by limiting the amount of time they spend elsewhere. I refuse to buy into materialism and consumerism (no pun intended again). In my opinion, feeding kids video games is like feeding their minds junk food. Just a thought...