When children don't like everything we offer them at the table, we call them "picky eaters" When we don't care for everything, or even try to hide a loathed food under a lettuce leaf, we blame the food itself or bad experiences we've had with it. We really like children to eat with enthusiasm the food that we've worked hard to prepare for them, and we don't easily excuse them when they don't.
What's it all about? Are children rejecting us when they won't eat, as we sometimes feel they are? Are there times in development when it's likely that children will eat a smaller variety of foods than they used to? Are there characteristics of the child that make a difference? And, is there anything we can do about any of this, or that we should do?
1. Developmental differences: When children are growing rapidly, they need a lot of calories, and they are likely to accept many different foods as fuel for growth. When growth slows down and the need for calories is less, children tend to choose preferred foods when they have a chance, and may eat little of or reject non-preferred foods. Knowing the times when growth is more rapid or slower, we can predict the ages at which "pickiness" is likely to emerge. Growth is very rapid through the first year, slowing down in the second year and later, only to pick up again as the child approaches puberty. Toddlers and preschoolers are often "picky", especially in contrast to their voracious and fairly indiscriminate appetites in their first months.
2. Temperamental differences: Some children have reactions to food that are based on biologically-determined ways of responding to the environment in general. One relevant temperamental characteristic is called "threshold of responsiveness"; it's a matter of noticing small differences between things or events. Children with low thresholds of responsiveness are repelled if a normally-preferred food is made slightly differently than usual or even at a different temperature. (I used to tell one of my children that the only way milk would ever be cold enough for him was if he climbed into the refrigerator to drink it-- he was put off by a glass of milk that had been poured five minutes before.) The issue for these children is not just about food, because they will also be concerned if their beds are made up too tightly or too loosely, or if a jacket sleeve has a knitted cuff when they are used to another kind.
3. Experiences: A major factor in food preference is the fact of past experience with a food. It's thought that breast-fed babies experience the flavors of family-preferred foods through the mother's milk, and that this experience forms a "flavor bridge" to later acceptance of those foods. When babies are offered "weaning foods" as first steps from a milk diet toward eating table food, those foods may or may not provide a "flavor bridge". A mother may think, "I never cook beets-- the baby's father and I hate ‘em-- but I know they're good for you, so I'll get some jars of pureed beets for the baby." (Once on table food, the child never sees another beet.) Texture as well as taste can play an important role in making a food familiar and acceptable. A friend recently told me that her daughter, who lives in New Mexico, had given her infant twins avocado as their first weaning food. They loved it, but then flatly turned down carrots-a food that feels different from avocado as well as tasting different. Older children who reject a food may find it acceptable after they've seen it on their plates many times without being urged to eat it. To understand these childhood behaviors, we need to keep in mind that young children have a sort of general neophobia, or avoidance of the unfamiliar, which probably is very useful in keeping them from eating holly berries or other items that may not be very good for them.
Can we do anything about "pickiness"? And, if we can, should we? To take the second question first, yes-- I think it's to a child's advantage to enjoy a varied diet. Different items of food provide somewhat different nutrients, so for a complete diet it's probably good not to limit the menu severely. In addition, while we don't want to encourage over-indulgence, food is one of the continuing pleasures of life, and a person has less fun if he or she cannot enjoy some of the foods others like.