@underneaththeash
Unfortunately they're still not old enough to know what's good for them. Vegetarian diets do not offer all the essential amino acids that children need. Fish oils are particularly healthy.
Humans are omnivores - whilst they're still growing they need to eat a range of meat, fish, vegetables, fruit, seeds etc....
They can do what they like when they leave home.
‘Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the lifecycle, including during pregnancy, lactation, infancy, childhood and adolescence. Appropriately planned vegetarian diets are healthful, nutritionally adequate and provide health benefits in the prevention and treatment of certain diseases.’ - World Health Organisation
‘With good planning and an understanding of what makes up a healthy, balanced vegan diet, you can get all the nutrients your body needs.’ - NHS UK
Many plant foods do offer complete proteins, for example quinoa, but there is no need to eat complete proteins in every meal. Eating a variety of plant based foods rich in protein (legumes, beans, soy, mock meats, nuts, etc) will provide all the essential amino acids that one needs. It is recommended vegans aim for 3-4 servings of these foods per day. One serving is just half a cup of lentils or a quarter cup of nuts or a cup of soy milk. protein deficiencies are extremely rare in the developed world as they go hand in hand with not meeting ones calorific needs, however it is possible for vegans to have less then optimal protein levels, especially of lysine, if they don’t take care to eat a balanced vegan diet (lentils, beans, soy, etc)
Instead of fish oil I take an algae based DHA supplement. If you don’t want to take supplements you can just eat foods rich in ALA as the body with convert this to DHA. Think walnuts, flaxseed, canola oil, etc.