Children rejecting broccoli and sprouts is not simply a preference for sweet things. Bitter perception is stronger in childhood and varies considerably between individuals for genetic reasons.
Bitter detection is a protective system
Many naturally occurring toxins are bitter, and sensitivity to bitterness functions as a warning. Rejection on tasting bitterness is a defensive response rather than a fussy one.
The response is strongest at the age when children begin moving independently and putting unfamiliar things in their mouths. The timing is not coincidental.
It softens with age, which is part of why adults tolerate coffee, dark chocolate and bitter greens that the same person refused as a child.
Children have more taste receptors
Taste receptor density is higher in childhood and declines across the lifespan. The same food therefore delivers a stronger signal to a child than to an adult.
This applies to other tastes too, which is why strong flavours in general can be overwhelming for young children rather than only bitter ones.
Parents tasting the same dish and finding it mild are not mistaken. Both perceptions are accurate reports of different sensory systems.
Genetic variation splits the population
Variation in bitter receptor genes means certain compounds, including those found in brassicas, taste intensely bitter to some people and barely register for others.
Within one family, siblings can differ. A child who genuinely cannot tolerate a vegetable another child eats happily is not being difficult.
This variation is inherited, so a parent who disliked the same foods at that age is often observing something they experienced themselves.
Repeated exposure changes acceptance slowly
Familiarity reduces rejection over time, and the number of exposures required is typically far higher than parents expect before a food is accepted.
Exposure counts even without eating. Seeing a food on the table, handling it and having it present without pressure all contribute.
Pressure works against this. Foods associated with conflict tend to be rejected more persistently, so the effort applied can extend the timeline rather than shorten it.
Preparation changes the chemistry
Cooking method alters bitterness measurably. Roasting concentrates sugars through caramelisation, while prolonged boiling can intensify the sulphurous compounds in brassicas.
Fat and salt suppress bitter perception, which is why the same vegetable is accepted with butter or oil and refused plain.
Where a child's diet is very restricted, growth is affected, or refusal extends across whole food groups, that pattern is worth discussing with a health visitor, dietitian or paediatric professional.