Children and Their Mothers Had the Same Bitter-Taste Gene. Only the Children Wanted More Sugar

A study of 143 children and their mothers found that a variant in the TAS2R38 bitter receptor predicted sensitivity to a bitter compound in both groups — but predicted sweet preference only in the children. What changed was not the gene.

Getting a five-year-old to eat broccoli is not purely a battle of wills. Children genuinely inhabit a different flavour world from adults — they reject bitterness more strongly and prefer sweetness more intensely, and both tendencies fade with age.

A study at the Monell Chemical Senses Center set out to test how much of that is written in a single gene.

The design

Researchers collected DNA from cheek cells of 143 children and their mothers, a racially and ethnically diverse sample, and genotyped TAS2R38 — a bitter taste receptor gene discovered only a few years earlier.

They grouped participants by the variant at position 49, where the gene codes either alanine or proline (rs713598, the A49P substitution). Homozygous bitter-insensitive individuals were labelled AA, heterozygotes AP, and homozygous bitter-sensitive PP.

Both children and mothers were then tested — using identical game-based, forced-choice procedures designed to work regardless of language development — for sensitivity to the bitter compound PROP and for sucrose preference (Mennella et al., Pediatrics, 2005, PMID: 15687429).

The split result

For bitter sensitivity, genotype predicted the outcome in both generations. PP individuals detected PROP at lower concentrations than AA individuals, whether they were seven or thirty-seven. The receptor does what a receptor does.

For sweet preference, the pattern held in the children and not in the mothers.

Same gene. Same genotype groups. The association with wanting sugar was visible in childhood and had faded by adulthood.

What that gap is telling you

The genotype did not change. Everything around it did — decades of eating, cultural food norms, learned preferences, the acquired adult tolerance for coffee, beer, grapefruit and dark chocolate that no child arrives with.

This is one of the cleanest illustrations available of a gene's effect being conditional on life stage and context. A variant with a measurable influence at seven can be undetectable at thirty-seven, for the same person.

It is also why "supertaster" language should be handled with care. TAS2R38 genotype does track sensitivity to a specific class of bitter compounds. It is not a global ranking of anyone's palate, and it does not determine what a person ends up enjoying.

What the app reports

Taste Perception reads your TAS2R38 genotype and places you in the bitter-sensitive, intermediate or insensitive group described in this research - that is, where you would have fallen among the participants had you taken part in that study.

If you are bitter-sensitive and drink your coffee black anyway, that is not a contradiction. It is the adult half of the finding — the part where exposure catches up with the receptor.