Hi blessed, I'm fairy new here with posting, so please forgive me if I say something that isn't part of the culture here. I'll start by saying I am not a vegetarian, but in my old age (of 40,lol) have learned to appreciate the lifestyle and foods that vegetarians eat. I love vegetable, eggplant and mushroom based meals- something I would have scoffed at in my 20s. But I still eat my share of meat.
I have a very good friend and two cousins who are, as well as a friend who is kosher (so when we dine out, she is essentially a vegetarian). One of my cousins is a strict, hard core vegan. Her child is 5, and she is raising him to be vegetarian (not vegan). I never asked her why not vegan, but I suspect she wants to make sure a) he is not as limited in social situations, and b) receiving enough dairy and protein and such. At his age, he definitely has an understating of why his family doesn't eat meat (yet his cousins who he spends a great deal of time with, eat it regularly). I don't know how she handles that, if and and when he asks why.
My other cousins child is also vegetarian, and my best friends kids eat meat (as does her husband).
As parents, we always want to instill good, positive values in our children. With the excretion of people who are BAD parents (and even though I don't know you, I'm guessing you don't fall into that category), like drug addicts and criminals, most of us believe we are doing the right thing and want our children to model our behaviors.
In your household, dad eats meat, and mom doesn't. And you are both good parents, who do what you do for your own reasons. You paved the way early, and guided them in a direction you believed was best. Then gave all of your other children the option of opting out.
I know it's a stretch, but it's kind of like religion (please, I'm not looking for a religion discussion here, just using it as a loose analogy). We raise our children in the same faith as ours, but when they grow up, it is their choice to continue in that faith, or turn to another (or none at all).
There's a discussion in the teen forum going on about kids not liking the same foods as we eat, and how some people have trouble with that. We provide them with the tools they need as children; the ground rules. No snacking before dinner, no pizza for breakfast, no meat on Fridays during Lent (in my house), soda only on special occasions, no meat mixed with dairy in my friends house, and no pork or shellfish ever!! As parents, we generally take issue when our kids want to do things we don't want them to. It's human nature. I'm assuming your other children are happy and healthy, right? And who's to say one or more of them won't go back to this lifestyle later on? They will still be influenced by you, and your reasoning for choosing this lifestyle, but they are also influenced by their peers. As they enter the teen years, it is likely that they may change their minds again (I'm surprised mine hasn't, at 14).