Genetically Wired to be Picky?

“Don’t worry. He’ll grow out of it.”

Yes, on first glance, my son is a picky eater, just like millions of other children around the world. Statistics claim that about 95% of children do grow out of their picky eating ways. For the remaining 5% however, the successful transition from vegetable shunning toddler into adventurous foodie remains a thing of fantasy. Oh, to dream the impossible dream…

Children and adults have distinctly different reactions to food, especially food they find unpalatable. Children respond to its sensory qualities; “it’s slimy, it stinks, it’s too chewy”. Adults tend to have perceptions and experiences that influence their behavior toward food; “vegetables are full of vitamins, so let’s find a way to make this one taste better”. Even among typical eaters, adults and children eat in different sensory realms.

The selective eater’s food experience is enhanced by anxiety. Where a typical eater senses food in an overall context, the selective eater will be acutely aware of multiple individual details in every tiny bite. It can be very overwhelming.

Even under optimum conditions, an individual’s sensory experience is very difficult to describe to another person. I once read that the Inuit have a phenomenal amount of different words to describe snow. It makes sense that a people that exist in a snow covered land would need more than a half-dozen ways to describe it. Colour. How do you describe periwinkle to someone who was born blind? I come across this concept more frequently with TJ as he tries to explain what he likes and dislikes about food. “I like the apple because it’s crunchy, but not the carrot because it’s not the right kind of crunchy.” What does that mean? It’s relevant to him. It’s jibberish to me. Crunchy is crunchy, right? Apparently crunchy is a spectrum that extends beyond loud, quiet, hard, soft and “bunfeckle” (TJ made that one up and neglected to share its meaning). We are trying to build a fluent food vocabulary to help me better understand how he perceives taste, texture and eating in general.

But will TJ grow out of his picky eating? Researchers have discovered concrete medical evidence that could explain why some children grow out their picky eating and others don’t.

Food neophobia peaks in most children between the ages of 2 – 6. In this study, researchers used cheek swabs to test genetic variations in the recently discovered bitter taste receptor gene, TAS2R38. This inherited gene influences our liking of sweet-tasting and rejection of bitter tasting foods. Foods from animal and plant sources pose the most significant risk of poisoning to children, dating back to the earliest days of the human race when a child would be old enough to locate food, but not experienced enough to know if it’s safe to eat.

This protective “bitter is bad for you, don’t eat it” mechanism has remained part of our genetic make-up, and appears to be quite sensitive in a large percentage of the pediatric population.

The two most common types of this taster gene are “AVI” (non-taster, recessive) and “PAV” (taster, dominant). By using phenylthiocarbamide (PTC), a soluble powder that either tastes very bitter or is virtually tasteless, researchers tested bitterness sensitivity by genetic make-up. Those with the genotype AVI/AVI typically cannot taste PTC, while those with PAV/PAV genotypes can detect very low concentrations of PTC mixed in water. Children with the genotype PAV/AVI, however had a much greater sensitivity to the bitter taste of PTC than their mothers with the same genotype, perhaps suggesting that heterozygous children become less sensitive to bitterness as they grow older and their sensory systems mature.

Another study of 65 preschoolers (age 3 ½ – 4 ½ years) observed that the children who could detect low concentrations of another bitter compound mixed in water consumed fewer vegetables than the group that could not. The researchers noted that 63% of the test group were “tasters”. Out of the group of 41 tasters, 14 children refused to try any of the vegetables vs. 2 out of the 24 non tasters. All of the children had been previously exposed to the foods used in this study several times.

This brings into question the idea that children will eventually try a new food simply by exposing them to it. The study of taster preschoolers supports a phenomenon present in other studies – approximately one third of any randomly selected group of children will not have anything to do with vegetables, regardless of the methods used or how many times it shows up in their field of vision.

That’s all very interesting, but what does it mean? Is food neophobia a genetic trait? To date, no one has compared genetic bitterness sensitivity and food neophobia in the same sample, however most studies indicate a need for further research in these areas.

US census data states there were 20,348,657 children aged 5-9 as of 2010. That 5% equates to over 1 million American children who will not outgrow their food neophobia, possibly because of their sensitivity to bitter tasting vegetables and/or the sensory qualities of food. That’s just one country’s data for a feeding dilemma that exists world-wide. These particular children perceive taste very differently or more intensely, and often have stronger aversive reactions to food textures than the general population.

More than pending recognition as an eating disorder by the mental health community, Selective Eating Disorder also appears to have genetic and medically valid origins. As the parent of a child with SED, I find all this research a lot more comforting than a dismissive “he’ll grow out of it.” Based on comments TJ has made about how food tastes to him, the likelihood that he is genetically wired to be sensitive to bitterness is a strong possibility. He will never grow out of his genes any more than he will outgrow his hazel-green eyes. It is just part of who he is.

For those who want to blame poor parenting skills for the creation of our picky eaters, statistically we may have documented research and science on our side. I did not create my picky eater. Evolution did.

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3 responses to “Genetically Wired to be Picky?

  1. My 54 year old spouse has always been tagged a “picky eater”. I found this aspect of my love challenging since cooking two different meals is time consuming and expensive. Over time, the descriptions of texture and the ability to percieve the most miniscule amount of thyme or black pepper brought me to the conclusion that my spouse is a super-taster and perhaps has SED. Unfortunately, my spouse is constantly defending food choices to famly and collegues who simply have no idea that this is real. Thank you

  2. My son, now 18 years of age, has had SED since he was a baby. It is reassuring to know that there is finally more awareness concerning this disorder. I hope the medical community finally wakes up and listens!

    • Thank you for your comment.

      I am thrilled to see more medical professionals mentioning SED or at the very least recognizing that selective eating is not something that just goes away nor is it a choice.

      I hope your son has found friends that support and respect him for being just who he is.

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