[{"data":1,"prerenderedAt":69},["ShallowReactive",2],{"guide:dominantTraits:en":3},{"updated":4,"faq":5,"sources":21,"html":40,"toc":41},"2026-10-16",[6,9,12,15,18],{"q":7,"a":8},"Are dimples a dominant trait?","They are often described that way, and dimples do tend to run in families. But no gene for dimples has been found, some researchers say there is no proof they are inherited at all, and dimples can come and go as a child grows.",{"q":10,"a":11},"Is curly hair dominant over straight hair?","There is no simple rule. Hair texture depends on many genes, different genes matter in different populations, and hormones, some medicines, age and treatments such as perms can change it too.",{"q":13,"a":14},"Do freckles run in families?","Yes, mostly through versions of the MC1R gene, the same gene linked to red hair and fair skin. The more of these versions a person carries, the more freckles they tend to have, and sunlight brings them out.",{"q":16,"a":17},"Can two parents who can't roll their tongue have a child who can?","Yes. Family studies found children who could roll their tongue born to parents who could not, identical twins sometimes differ, and some children learn to do it later. Tongue rolling is not a simple one-gene trait.",{"q":19,"a":20},"Can we predict which of these traits our baby will have?","Not really. Traits like dimples, freckles and curls depend on many genes, on chance and sometimes on sunlight or age. Our calculators give rough odds for eye colour, hair colour and height, and the AI generator is a fun way to imagine a face.",[22,25,28,31,34,37],{"label":23,"url":24},"National Human Genome Research Institute, Talking Glossary of Genomic and Genetic Terms: Dominant","https:\u002F\u002Fwww.genome.gov\u002Fgenetics-glossary\u002FDominant",{"label":26,"url":27},"McDonald JH. Myths of Human Genetics (dimples, cleft chin, earlobes, tongue rolling). University of Delaware, 2011","https:\u002F\u002Fudel.edu\u002F~mcdonald\u002Fmythintro.html",{"label":29,"url":30},"MedlinePlus Genetics (US National Library of Medicine): Are facial dimples determined by genetics?","https:\u002F\u002Fmedlineplus.gov\u002Fgenetics\u002Funderstanding\u002Ftraits\u002Fdimples\u002F",{"label":32,"url":33},"MedlinePlus Genetics (US National Library of Medicine): Is hair texture determined by genetics?","https:\u002F\u002Fmedlineplus.gov\u002Fgenetics\u002Funderstanding\u002Ftraits\u002Fhairtexture\u002F",{"label":35,"url":36},"Bastiaens M, ter Huurne J, Gruis N, et al. The melanocortin-1-receptor gene is the major freckle gene. Human Molecular Genetics 2001;10(16):1701-1708","https:\u002F\u002Fdoi.org\u002F10.1093\u002Fhmg\u002F10.16.1701",{"label":38,"url":39},"Praetorius C, Sturm RA, Steingrimsson E. Sun-induced freckling: ephelides and solar lentigines. Pigment Cell & Melanoma Research 2014;27(3):339-350","https:\u002F\u002Fdoi.org\u002F10.1111\u002Fpcmr.12232","\u003Ch2 id=\"mostly-not-at-least-not-in-the-way-school-taught-it\">Mostly not, at least not in the way school taught it\u003C\u002Fh2>\n\u003Cp>Many biology lessons present dimples, freckles, curly hair, a cleft chin, free earlobes and tongue rolling as neat one-gene traits, each with a dominant and a recessive version. When the geneticist John McDonald went back to the family and twin studies behind several of these claims, most did not fit that pattern. Some traits are shaped by several genes, some by sunlight or age as well, and for dimples there is little published evidence of a genetic cause at all.\u003C\u002Fp>\n\u003Cp>That does not mean genes play no part. It means the simple chart cannot tell you what your baby will look like.\u003C\u002Fp>\n\u003Ch2 id=\"what-dominant-and-recessive-mean\">What dominant and recessive mean\u003C\u002Fh2>\n\u003Cp>Everyone has two versions of each gene, one from each biological parent. When the two versions differ, often only one of them shows. That one is called dominant, and the other, whose effect is masked, is called recessive. A recessive trait only shows when a child inherits the recessive version from both parents, which is how it can appear in a child of two parents who do not show it.\u003C\u002Fp>\n\u003Cp>This works well when one gene does most of the work, which is roughly the case for blood groups. The \u003Ca href=\"\u002Ftools\u002Fbaby-blood-type-calculator\">blood type calculator\u003C\u002Fa> is built on it. Most visible features are different: many genes each add a small push, and the result is a range rather than two neat boxes.\u003C\u002Fp>\n\u003Ch2 id=\"dimples\">Dimples\u003C\u002Fh2>\n\u003Cp>Dimples do tend to run in families and are usually described as dominant. Yet it is not known which genes are involved, and some researchers point out that there is no published proof that dimples are inherited. They also change over a lifetime. Many babies have dimples from baby fat that disappear as the fat goes, other children only develop them later, and for some people they last only until adolescence or young adulthood.\u003C\u002Fp>\n\u003Ch2 id=\"cleft-chin\">Cleft chin\u003C\u002Fh2>\n\u003Cp>A cleft chin is another classroom favourite. The family studies that exist do not fit the idea that it comes from a single dominant version of a gene, so it is a poor example of simple inheritance.\u003C\u002Fp>\n\u003Ch2 id=\"freckles\">Freckles\u003C\u002Fh2>\n\u003Cp>Freckles have one clear genetic link: the MC1R gene, which is also tied to red hair and fair skin. In a large study, people with one MC1R variant had about 3 times the risk of childhood freckles, and people with two variants about 11 times. The more variants, the more freckles, and nearly everyone with freckles carried at least one variant.\u003C\u002Fp>\n\u003Cp>That is a dose effect rather than a classic dominant trait. Genes are not the whole story either: freckles of this kind are largely genetic, but sunlight is what brings them out. If red hair runs in your families, the \u003Ca href=\"\u002Ftools\u002Fbaby-hair-color-calculator\">hair colour calculator\u003C\u002Fa> lets you take that into account.\u003C\u002Fp>\n\u003Ch2 id=\"curly-hair\">Curly hair\u003C\u002Fh2>\n\u003Cp>Genes play a major role in hair texture, but no single "curly" gene decides it. Many genes are likely to contribute, and different ones seem to matter in people of different ancestries: a variant of the TCHH gene is linked to hair texture in people of northern European ancestry, for example. Hormones, some medicines and treatments such as perms or relaxers can change hair, and texture can also change with age. So there is no rule that curly beats straight.\u003C\u002Fp>\n\u003Ch2 id=\"earlobes-and-tongue-rolling\">Earlobes and tongue rolling\u003C\u002Fh2>\n\u003Cp>Earlobes do not really come in two types, free and attached. The attachment point varies continuously from person to person. There is probably some genetic influence, but family studies have found children with free earlobes born to two parents with attached ones, which a one-gene model says cannot happen.\u003C\u002Fp>\n\u003Cp>Tongue rolling has an even clearer story. In one study of 33 pairs of identical twins, who share the same genes, 7 pairs included one twin who could roll their tongue and one who could not. Parents who could not roll their tongue had children who could, and some children who cannot do it at first learn it later. Alfred Sturtevant, the geneticist who first described it as an inherited trait in 1940, later said he was embarrassed to see it still listed as a simple Mendelian case.\u003C\u002Fp>\n\u003Ch2 id=\"what-you-can-and-cannot-expect\">What you can and cannot expect\u003C\u002Fh2>\n\u003Cp>Your baby will inherit a mix of both of your genes, but which versions they get is down to chance. A trait neither of you shows can appear, and one you both have may not.\u003C\u002Fp>\n\u003Cp>For eye colour, hair colour and height, our free tools give rough odds from what each of you looks like: the \u003Ca href=\"\u002Ftools\u002Fbaby-eye-color-calculator\">eye colour calculator\u003C\u002Fa>, the \u003Ca href=\"\u002Ftools\u002Fbaby-hair-color-calculator\">hair colour calculator\u003C\u002Fa> and the \u003Ca href=\"\u002Ftools\u002Fchild-height-predictor\">child height predictor\u003C\u002Fa>. Each one explains its method and its limits.\u003C\u002Fp>\n\u003Ch2 id=\"imagine-it-for-fun\">Imagine it, for fun\u003C\u002Fh2>\n\u003Cp>If you are curious what a face with your dimples and your partner's curls might look like, the \u003Ca href=\"\u002Fgenerate\">AI baby photo generator\u003C\u002Fa> blends a photo of each of you into an imagined child. It is a playful picture, not genetics: it cannot see which hidden versions of genes either of you carries, so take it as entertainment, not a prediction.\u003C\u002Fp>\n",[42,45,48,51,54,57,60,63,66],{"id":43,"text":44},"mostly-not-at-least-not-in-the-way-school-taught-it","Mostly not, at least not in the way school taught it",{"id":46,"text":47},"what-dominant-and-recessive-mean","What dominant and recessive mean",{"id":49,"text":50},"dimples","Dimples",{"id":52,"text":53},"cleft-chin","Cleft chin",{"id":55,"text":56},"freckles","Freckles",{"id":58,"text":59},"curly-hair","Curly hair",{"id":61,"text":62},"earlobes-and-tongue-rolling","Earlobes and tongue rolling",{"id":64,"text":65},"what-you-can-and-cannot-expect","What you can and cannot expect",{"id":67,"text":68},"imagine-it-for-fun","Imagine it, for fun",1793362220457]