Personally, aside from the obvious health benefits, I think it is a wonderful thing to raise a compassionate child, with a respect for other living animals and an understanding that they do not need to harm any of their fellow creatures by the necessary, life-maintaining act of eating.
With common sense and care to ensure that a child is receiving the necessary protein, iron, calcium, vitamin D and B (especially B-12) vitamins in their diet, a vegan or vegetarian child has been observed in some studies to be less likely to exhibit violent and antisocial tendencies, early onset puberty and obesity. This is a result of the omission of meat, the steroids and hormones found in meat (natural and fed to the animal) and pesticides (more prevalent in meat than with properly washed or organic fruit and vegetables). Not to mention the higher levels of saturated fats, salts and sugar more commonly found in meat-eating households.
With the ever-increasing prevalence of violence and obesity in our children, both the health benefits and the social benefits with being raised as a compassionate being, seem obvious, even though hotly debated.
Plan your vegan/vegetarian diet well for both the health and wellbeing of your children and yourselves. Not only will you avoid the problems mentioned above, but you will put your child on the path to healthy eating habits and the avoidance of further health problems such as high blood pressure, heart disease and many cancers.