Average children in large/very large families have quite a tenuous existence.They never have enough, even the rudimentary things. The socioeconomic situation in their families are extremely tight. Large/very large families are extremely lucky if there is money for food, clothing, & shelter, if that. It's commonplace for such children to do without. If they want things that normal children have, they would have to take either an afterschool or weekend job to purchase things like movie money, school supplies, & even clothes.
It is quite normative for children in large/very large families to go hungry because there are so many mouths to feed. If it weren't for school breakfasts/lunches, many children in large/very large families would go hungry.The same applies to healthcare, such children only receive medical care from school physicians. The majority of large/very large families are extremely socioeconomic poor, even impoverished or penurious so it's quite de rigueur for them to depend upon donations from outside sources including relatives, churches, & charitable organizations for items such as clothing, even food.
Children in large/very families oftentimes consume inferior quality food because better quality of food are too expensive for the average large/very large family. Meat, fish & other high quality proteins are out of reach for those in large/very large families. They often have to consume meat substitutes in addition to non-nutritious food. As a result of this inferior diet, they are oftentimes unhealthy. Since struggle & doing without is a normative way of life for children in large/very large families, they believe that everyone is/should have the same lifestyle as theirs.
However, there are children who do not have a rigorous lifestyle.In fact, they are born into socioeconomic circumstances which affords them almost every conceivable opportunities & choices. This situation aptly describes average children in small families. When children from large/very large families see the contrast in lifestyles between them & children in small families, they feel angry at their circumstances, even their parents. However, instead of displacing such anger at their parents & familial situation,they displace such anger towards children in small families.They hate children in small families because the latter is living the life they wish they had instead of the current hellish life they are living.