Man of Honour
I'd pass on their details to child protective services. Vegan diets are nutritionally deficient in several vital vitamins for a child's development. By forcing their kids on to a vegan diet, essentially it's abuse by virtue of neglecting their welfare.
In the study, published April 9, 2012, in the Archives of Internal Medicine, a team of Harvard researchers looked for statistical links between meat consumption and cause of death. The populations scrutinized included about 84,000 women from the Nurses' Health Study and 38,000 men in the Health Professionals Follow-up Study.
People in the study who ate the most red meat tended to die younger, and to die more often from cardiovascular disease and cancer. These people also tended to weigh more, exercise less, smoke tobacco more, and drink more alcohol than healthier people in the study. Yet even when the researchers compensated for the effects of unhealthy lifestyle, mortality and meat remained associated.