Eyes & Vision 4 calculators
Calculate brown, blue, green, hazel and grey probabilities using OCA2 and HERC2 gene models.
Open Calculator →Predict monolid, hooded, almond, or round eye shapes from parental features and PAX gene variants.
Open Calculator →Estimate X-linked red-green color blindness probability based on family carrier history and OPN genes.
Open Calculator →Calculate the probability of differently colored eyes using melanin distribution and development genetics.
Open Calculator →Hair 5 calculators
Predict black, brown, blonde, or red hair using polygenic pigment models and MC1R gene analysis.
Open Calculator →Find out if your baby will have straight, wavy, curly, or coily hair using TCHH gene inheritance models.
Open Calculator →Estimate hereditary androgenetic alopecia risk based on parental and grandparental hair-loss patterns.
Open Calculator →Predict beard colour based on scalp hair genetics and MC1R variant inheritance for male children.
Open Calculator →Calculate clockwise vs counter-clockwise hair whorl probability from genetic and developmental models.
Open Calculator →Skin & Complexion 4 calculators
Explore likely skin tone range using the Fitzpatrick scale , especially useful for mixed-ethnicity families.
Open Calculator →Determine cool, warm, or neutral undertone probability based on parental pigmentation genetics.
Open Calculator →Discover how the MC1R gene drives freckle formation and the probability of your child having them.
Open Calculator →Understand the genetic basis of congenital moles and birthmarks and their inheritance probability.
Open Calculator →Face & Features 9 calculators
Predict oval, round, square, heart, or diamond face shape from parental facial bone structure genetics.
Open Calculator →Calculate probable nose bridge height, width, and tip shape from polygenic facial feature inheritance.
Open Calculator →Predict lip fullness, Cupid's bow shape, and overall proportions based on parental genetics.
Open Calculator →Find out the likelihood of facial dimples using zygomaticus muscle variation and dominant inheritance analysis.
Open Calculator →Calculate cleft chin probability based on dominant genetic factors passed from both parents.
Open Calculator →Predict attached or free earlobes using classical Mendelian dominant and recessive inheritance grids.
Open Calculator →Estimate widow's peak hairline probability using dominant inheritance pattern analysis.
Open Calculator →Predict thick, thin, arched, or straight eyebrows from parental feature genetics.
Open Calculator →Understand inherited facial symmetry tendencies based on parental developmental gene patterns.
Open Calculator →Height & Growth 4 calculators
Estimate adult height using the validated mid-parental formula. Supports cm and feet/inches input.
Open Calculator →Track baby height percentiles and compare against WHO/CDC growth chart standards by age.
Open Calculator →Estimate likely birth weight range based on parental size, gestation, and hereditary growth patterns.
Open Calculator →Predict baby head circumference range using parental measurements and polygenic brain development models.
Open Calculator →Body Traits 8 calculators
Predict left-handed vs right-handed probability from parental handedness and genetic marker analysis.
Open Calculator →Calculate tongue rolling ability probability using dominant Mendelian inheritance analysis.
Open Calculator →Predict hitchhiker's thumb hyperextension probability using recessive inheritance pattern models.
Open Calculator →Estimate hypermobility probability from inherited connective tissue and collagen gene variants.
Open Calculator →Calculate second-toe-longer-than-big-toe probability from polygenic foot structure inheritance.
Open Calculator →Calculate ABO and Rh blood type probabilities for your baby from both parents' known blood types.
Open Calculator →Predict lactase persistence probability based on LCT gene variants from parental ancestry patterns.
Open Calculator →Calculate PTC bitter taste sensitivity probability based on TAS2R38 gene variant inheritance.
Open Calculator →Baby & Development 5 calculators
Generate a combined parental facial feature estimate to visualise possible baby appearance.
Open Calculator →Understand when and how eye colour changes from birth through the first 3 years of life.
Open Calculator →Track how melanin production develops in babies and how skin tone evolves post-birth.
Open Calculator →Explore traditional and scientific gender prediction methods including the Chinese calendar chart.
Open Calculator →Calculate your estimated due date using Naegele's rule and last menstrual period method.
Open Calculator →No calculators found.
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How TraitGen calculators work
Every calculator on TraitGen is built on genetic models drawn from peer-reviewed research. Simple traits like earlobe type, dimples, and tongue rolling use classical Mendelian inheritance grids , the same Punnett square logic taught in biology and validated for over a century. Complex polygenic traits like eye colour, hair colour, height, and skin tone use multi-gene probability models that account for contributions from both parents and in many cases grandparents too.
All calculations happen entirely in your browser. Nothing you enter is transmitted to any server or stored anywhere. Your family's genetic information stays completely private on your own device.
🧬 Mendelian traits
Single-gene traits with clear dominant/recessive patterns: dimples, earlobes, tongue rolling, cleft chin, hitchhiker's thumb. Outcomes follow predictable Punnett square probabilities.
🧩 Polygenic traits
Complex traits controlled by many genes: eye colour (16+ genes), height (700+ variants), skin tone (170+ variants). Results are probability ranges, not certainties.
🔒 Private by design
All calculations run locally in your browser using JavaScript. No data is collected, transmitted, or stored. You can verify this by checking that calculators still run offline after the page loads.
📚 Research-based
Models reference published genetics research from the NIH, OMIM, and peer-reviewed human genetics journals. Claims are traceable to primary sources, not guesswork.
Frequently asked questions about our calculators
Our calculators provide probability estimates based on established genetic models, not guaranteed outcomes. For simple Mendelian traits (tongue rolling, earlobe type, dimples) the models are well validated and accuracy is high. For complex polygenic traits (eye colour, height, skin tone) the results are probability distributions because hundreds of gene variants contribute to the outcome. Think of results as scientifically informed estimates rather than certainties. The more parental and grandparental data you provide, the more refined the estimate.
No. Every calculator on TraitGen is completely free and requires no sign-up, no account, and no payment. Just open any calculator, enter the parental information, and get your results instantly. We believe genetics education should be accessible to every family without barriers.
Your data is completely private. All calculations run locally in your browser using JavaScript. Nothing you enter is sent to our servers, stored in a database, or shared with any third party. You can verify this yourself by checking network requests in your browser's developer tools , you will see no data transmission when you run a calculation.
A dominant trait is expressed when at least one copy of the relevant allele is present. A recessive trait requires two copies , one from each parent , to be expressed. For example, dimples are dominant: if either parent has the dimple allele, a child has a good chance of inheriting them. Red hair is recessive: both parents must carry the MC1R variant for a child to have red hair. Many traits fall between these extremes due to incomplete dominance or polygenic inheritance.
Genetic inheritance is probabilistic, not deterministic. Even when the genetics strongly favour a particular outcome (e.g. 75% probability of brown eyes), the other outcomes remain possible. Showing percentages is scientifically accurate and honest , it reflects how genetics actually works rather than giving a false single-answer prediction. The percentages represent the probability distribution across possible outcomes given the parents' known genetics.
Yes, and this is one of the most popular use cases. Expecting parents use our calculators to explore which traits are genetically possible for their baby. Remember that results are probabilities , the actual outcome will depend on which specific combination of alleles the baby inherits, which is random within the genetic framework the parents provide. The real result is always a wonderful surprise.
Recessive traits can skip generations because they are carried silently by people who do not express them. For example, a brown-eyed person can carry a blue-eye allele inherited from a grandparent. If they partner with someone else carrying the same recessive allele, their child can unexpectedly express the trait. This is why knowing grandparent traits improves prediction accuracy , it helps identify these hidden recessive carriers in the parent generation.
No. TraitGen calculators are strictly educational tools. They are not designed for medical decisions, health risk assessments, paternity testing, or clinical use of any kind. For anything medically relevant related to genetics , hereditary conditions, disease risk, chromosomal concerns , please consult a certified genetic counsellor or your healthcare provider. Our tools are for curiosity, education, and family planning exploration only.
Understanding genetics and baby trait prediction
Human genetics is the study of how biological information is passed from parents to children through DNA. Each person inherits approximately 3 billion base pairs of genetic code , half from their mother and half from their father. Within this code, specific sequences called genes determine everything from eye colour to height to whether you can roll your tongue.
What are alleles?
Alleles are different versions of the same gene. For each gene, you inherit two alleles , one from each parent. The combination of alleles you carry determines your genotype, while the traits you visibly express form your phenotype. When alleles differ, dominant ones are usually expressed over recessive ones.
What is Mendelian inheritance?
Named after Gregor Mendel, this describes how single-gene traits follow predictable dominant and recessive patterns. Punnett squares map the possible allele combinations from two parents, giving exact probabilities for each outcome. It works well for simple traits like earlobe attachment or tongue rolling.
What is polygenic inheritance?
Most interesting traits , height, eye colour, skin tone, hair colour , are controlled by multiple genes simultaneously. Each gene contributes a small additive effect. The result is a continuous spectrum of outcomes rather than discrete categories, which is why these traits show so much variation across families and populations.
Why add grandparent data?
Grandparent data helps identify hidden recessive alleles that parents carry but do not express. A brown-eyed parent with a blue-eyed grandparent is likely a carrier of blue-eye genes. Including this information significantly improves the accuracy of probability estimates for recessive and polygenic traits.
What is incomplete dominance?
Some traits do not follow strict dominant/recessive rules. Instead, the child expresses an intermediate phenotype blending both parental alleles. Hair texture is a good example: straight and curly parents often produce wavy-haired children rather than clearly one or the other. This blending is called incomplete dominance.
What does penetrance mean?
Even when a person carries the genetic variant for a trait, it does not always appear visibly. This is called incomplete penetrance. Dimples are a good example , they are technically dominant but do not always develop even when the gene variant is present, due to developmental variation in muscle attachment geometry.