This was the first study to use a twin design to explore if mothers vary their feeding practices for twin children who differ in their fussy eating. As hypothesized, mothers exerted differential levels of ‘pressure to eat’ and reported differential use of food as a reward when one twin was fussier than the other. In a subset of twins who were the most discordant (highest quartile) in fussy eating, (‘food fussiness’ difference score ≥ .50), the results were the same. Mothers reported more ‘pressure to eat’ and ‘instrumental feeding’ when feeding the fussier twin, although differences in parental feeding practice scale scores were small. However, the feeding scales used in this study were not designed as a clinical tool, therefore it is difficult to determine the clinical significance of these differences. Using this novel twin design approach, we demonstrated that mothers of twins who differ in their ‘food fussiness’ may use some different feeding practices with each child. These findings can be interpreted in terms of a child-responsive model of the parent–child feeding relationship and may indicate that parents adopt specific feeding practices in response to their child’s fussy eating tendencies, even in the early toddler period.

The between-family analyses differed slightly from the within-in family analyses insofar as fussy eating was also significantly negatively associated with ‘restriction’, such that fussier children were less restricted for foods high in sugar and fat. The null finding in the within-family analysis for ‘restriction’ may reflect the low within-family variation for this particular parental feeding style, which indicates that ‘restriction’ may be more of a global parental policy than a child-responsive strategy to manage the child’s emerging appetitive traits.

A considerable body of evidence supports the positive cross-sectional association between fussy eating and pressuring feeding practices [10, 27, 28], and findings from this study indicate that this relationship is present from a young age. Parents may intuitively pressure their child to eat to encourage food intake and weight gain, although prospective and experimental studies suggest that pressure may be associated with poorer food intake [8], lack of interest in food [9], and lower weight gain [14]. Nevertheless, it isn’t clear that pressuring a child to eat directly worsens fussy eating behaviors and some degree of “pressure” may serve to mitigate fussy eating difficulties, especially in the short term [29]. Irrespective of the efficacy of this parent feeding strategy, findings from the current study demonstrate that mothers may attempt to manage fussy eating behaviors by pressuring children to eat.

The positive association between ‘food fussiness’ and ‘instrumental feeding’ is in line with previous studies of mothers with fussy children who reported using favored foods as rewards for eating healthy foods or for behaving well [30]. While rewarding a child for eating a less preferred food with a preferred food may increase the child’s intake of the less preferred food in the short term (i.e. for that particular eating occasion), employing a means-end strategy has been shown to negatively shift a child’s preference for the target food in the longer term [11]. Parents appear to employ a variety of techniques to counter food rejection, and the current study suggests that mothers may respond to differences in fussy eating between twin siblings by using a greater level of food rewards with the fussier child. However, relatively few mothers (n = 30) reported different levels of ‘instrumental feeding’ for each twin. Differential maternal use of ‘instrumental feeding’ between twins discordant for ‘food fussiness’ is likely to be subtle (mean difference = .01), and as previously mentioned, the clinical significance of this finding is questionable. In comparison to ‘pressure to eat’, ‘instrumental feeding’ seems less influenced by child behaviour.

The inverse association between fussy eating and restriction of high fat or high sugar foods in the between-family analyses contrast with findings from previous studies. The majority of cross-sectional studies in older children have reported that mothers of fussy eaters were more likely to restrict their child’s food intake [9, 10, 31, 32]. Previous studies have speculated that parents may restrict fussy eater’s food intake for health reasons [32], and perhaps believe that withholding palatable, energy-dense foods from the child may encourage consumption of rejected foods, such as fruit and vegetables [18]. It has been hypothesized that restriction could increase preference for the restricted food [33], potentially exacerbating fussy eating, however this hypothesis is yet to be confirmed.

Factors that may account for the difference between previous findings and ours include the young age of our sample and the use of a different tool to measure restriction. Most past studies used the ‘restriction’ subscale from the CFQ which asks about restriction of the child’s “favorite foods” (which does not necessarily mean foods high in sugar or fat); does not ask about restriction of portion sizes, and does not discriminate between limiting a child’s access to food and using food as a reward or in exchange for good behavior. There was very little difference in the use of restriction within families, even when twins were discordant in ‘food fussiness’. This suggests that restriction reflects a more general feeding practice rather than a child responsive strategy, and it may indicate that mothers who are less restrictive encourage greater fussiness in their children because they become accustomed to enjoying unlimited access to foods high in sugar and fat, and are therefore more likely to reject less palatable foods such as vegetables. It may also be the case that it is more difficult to vary levels of restriction with two twins than it is to use differing levels of pressure or food as reward. Qualitative research may help to better understand the relationship between ‘restriction’ and fussy eating in toddlerhood.

Few studies have examined longitudinal relationships between parental feeding practices and children’s fussy eating behavior. Indeed, to the authors’ knowledge, prospective studies have only examined whether particular feeding practices (mainly ‘pressure to eat’ or ‘restriction’) are associated with greater subsequent food fussiness [1, 9] or lower child weight [34], rather than the reverse direction. In a recent Australian study of parents of 2- to 5- year old children, associations between feeding practices (‘restriction’ and ‘pressure to eat’) and ‘food fussiness’ one year later were found to attenuate when controlling for additional covariates, for example, child temperament [35]. The NOURISH RCT found that in comparison to ‘usual care’, anticipatory guidance on early feeding improved responsive feeding practices in mothers [36] and resulted in improved dietary outcomes, food preferences and eating behaviors in children 3.5 years after the intervention [37]. However, no differences were observed in children’s ‘food fussiness’ between the control and intervention group, suggesting that feeding practices may not be able to influence fussy eating behaviors. Longitudinal analysis of the potentially bidirectional effects between ‘food fussiness’ and parental feeding practices are needed to fully explore the complexities of the relationship and to understand how these may change over the course of development.

Strengths, limitations and future directions

Children in this study were very young (16-months old), allowing us to capture fussy eating as it emerged. The twin design allowed us to control for a number of potentially confounding factors pertaining to aspects of the early environment shared by twin pairs, providing stronger evidence for the idea that mothers adapt their feeding practices to each child’s emerging eating behaviors, in a child-responsive framework. Lastly, the sample was large, and therefore reliable associations between parental feeding practices and child ‘food fussiness’ were established, while adjusting for a range of individual-level covariates including child weight. Consequently, the findings suggest that parents adapt their feeding practices to accommodate their child’s fussiness, independently of their weight.

Twins are born earlier and smaller than singletons, and there may be more concern about early growth while twin children “catch up”. Parents may be more likely to pressure and less likely to restrict their twin children compared to singletons. However, there was variation in the fussiness (and weight) of children, and weight and gestational age were controlled for in the analysis. There is no reason to believe that the relationships between parental feeding and fussiness would be different in a twin sample. The scales used in the current study were adapted for the younger age of the children; but these scales need to be formally validated in toddlers. The internal reliability for the ‘pressure to eat’ and ‘instrumental feeding’ scales were low and did not reach the recommended Cronbach’s Alpha value of 0.70 [38]. While the within-family design may support a child-responsive feeding model, the data in this study were nevertheless cross-sectional and thus directionality cannot be determined. A longitudinal within-family study investigating changes in both ‘food fussiness’ and parental feeding practices from toddlerhood to early childhood would provide a greater understanding of directionality.