Genetics
Baby Eye Color Prediction: How Genetics Decides
Predict your baby's eye color from both parents' eyes. See the probability chart, how grandparents shift the odds, and why eye color predictions are estimates, not guarantees.
9 min read
Genetics blog
Genetics guides, Punnett square tutorials, and calculator help
Practical articles for students, teachers, and biology learners who want clear explanations of inheritance, probability, genotypes, phenotypes, and genetic calculator results.
GeneticsFeatured article
Baby Blood Type Chart: What Will My Baby Have?
A baby's blood type comes from both parents' ABO and Rh genes. See the full inheritance chart for every parent combination, plus how the Rh factor is passed down.
10 min read
Latest articles
Genetics
Can Brown-Eyed Parents Have a Blue-Eyed Child?
Yes, two brown-eyed parents can have a blue-eyed baby if both carry a hidden blue-eye variant. Here is how eye color inheritance really works, and why it is not so simple.
10 min read
Genetics
GC Content and Melting Temperature
GC content is the percentage of G and C bases in a sequence, and it sets the melting temperature. Learn the Tm formulas, from the Wallace rule to nearest-neighbor, with examples.
11 min read
Genetics
How to Calculate Oligo Concentration
Calculate oligo concentration from OD260 using the Beer-Lambert law and the extinction coefficient. Convert between OD260, nmol, micrograms, and micromolar with worked examples.
12 min read
Genetics
How to Resuspend and Dilute Oligos
Resuspend a dried oligo to a 100 micromolar stock by adding microliters of buffer equal to ten times the nanomoles. Then dilute to working concentration with C1V1 = C2V2.
10 min read
Genetics
Oligo Secondary Structure: Hairpins and Dimers
Oligo secondary structures, hairpins, self-dimers, and heterodimers, reduce primer performance. Learn how they form, how to read delta G, and how to fix problem oligos.
11 min read
Genetics
PCR Primer Design Guidelines
Design PCR primers that work: 18 to 25 bases, 40 to 60 percent GC, matched melting temperatures, a 3-prime GC clamp, and no hairpins or dimers. A practical guide with a checklist.
12 min read
Genetics
What Is an Oligonucleotide?
An oligonucleotide is a short, single-stranded piece of synthetic DNA or RNA, usually 15 to 25 bases long. Learn what oligos are, how they are made, and what they are used for.
10 min read
Genetics
What Affects the Mutation Rate?
The mutation rate is shaped by DNA replication fidelity, repair systems, mutagens, sequence context like CpG sites, parental age, and the drift-barrier set by population size.
11 min read
Genetics
How to Calculate Mutation Rate
Calculate mutation rate two ways: the direct trio method (de novo mutations divided by callable sites) and the indirect phylogenetic method (divergence over time). Worked examples included.
14 min read
Genetics
Mutation Rate in Evolution and Disease
Mutation rate shapes evolution, cancer, viral drug resistance, and the molecular clock. Here is how the rate of new mutations drives both adaptation and disease across biology.
14 min read
Genetics
Mutation Rate vs Substitution Rate
Mutation rate is how fast new mutations arise; substitution rate is how fast they fix in a population. For neutral alleles they are equal (k = u), the heart of the molecular clock.
12 min read
Genetics
Mutation-Selection Balance Explained
Mutation-selection balance is the equilibrium where mutation adds deleterious alleles as fast as selection removes them. For recessive alleles the frequency settles at q = sqrt(mu/s).
13 min read
Genetics
What Is Mutation Rate? (Explained)
Mutation rate is how often new genetic changes arise, usually per base pair per generation. Learn what mutation rate means, how it is measured, and the human rate of about 1.2 x 10^-8.
10 min read
Genetics
What Causes Linkage Disequilibrium? (6 Forces)
Linkage disequilibrium is created by physical linkage, genetic drift, selection, admixture, bottlenecks, and mutation. Here is how each force generates LD, even between unlinked loci.
12 min read
Genetics
D' vs r²: Which LD Measure Should You Use?
D' and r² both measure linkage disequilibrium but answer different questions. Use D' for recombination and haplotype blocks, r² for prediction and GWAS tagging. Here is why.
12 min read
Genetics
How to Calculate Linkage Disequilibrium (D, D', r²)
Calculate linkage disequilibrium step by step: the D coefficient, D' normalization, and r² from haplotype frequencies. Full worked example with the formulas explained.
15 min read
Genetics
LD Decay and Recombination Explained
Linkage disequilibrium decays over generations as recombination breaks up allele associations. Learn the decay formula, why distance matters, and how haplotype blocks form.
13 min read
Genetics
Linkage Disequilibrium in GWAS Explained
Linkage disequilibrium makes genome-wide association studies possible through tag SNPs, but it also means hits aren't always causal. Here is how LD drives GWAS, fine-mapping, and imputation.
14 min read
Genetics
What Is Linkage Disequilibrium? (LD Explained)
Linkage disequilibrium (LD) is the non-random association of alleles at different loci. Learn what LD means, how it differs from linkage, and why it matters in genetics.
10 min read
Genetics
AP Biology Punnett Squares & the Chi-Square Test
Master AP Biology genetics: Punnett squares, the chi-square goodness-of-fit test, degrees of freedom, critical values, and worked practice problems with conclusions.
16 min read
Genetics
Blood Type Calculator: What Will My Baby's Type Be?
Predict your baby's blood type from the parents' types. Covers ABO and Rh inheritance, full parent-combination charts, Rh incompatibility, and why O and AB surprise people.
16 min read
Genetics
How to Calculate Allele Frequency From Genotypes
Learn how to calculate allele frequency from genotype counts using the counting method, p = (2·AA + Aa) / 2N, plus the genotype-frequency method and worked examples.
16 min read
Genetics
Cat Coat Genetics: Predicting Calico & Tortie Colors
How cat coat color genetics works: the X-linked orange gene, why calico and tortoiseshell cats are almost always female, and how to predict kitten colors.
15 min read
Genetics
Codominance Examples: Blood Type, Roan & Sickle Cell
The clearest codominance examples explained: ABO blood type, roan coat color, and sickle cell trait, with worked Punnett squares and genotype tables.
15 min read
Genetics
Coefficient of Relationship vs Inbreeding (r vs F)
The coefficient of relationship (r) measures how related two individuals are; the inbreeding coefficient (F) measures one individual's autozygosity. Here is how r and F differ and connect.
11 min read
Genetics
Common Punnett Square Mistakes and How to Fix Them
The most common Punnett square mistakes and how to fix them: gamete errors, genotype vs phenotype ratios, sex-linkage slips, and the dominance misconception.
16 min read
Genetics
Dihybrid Cross: How to Get the 9:3:3:1 Ratio (4×4 Punnett Square)
A dihybrid cross gives a 9:3:3:1 phenotype ratio. Learn how to find the four gametes, fill the 16-box grid, and use the product rule, with worked pea examples.
16 min read
Genetics
Dog Coat Color Calculator: Predict Puppy Colors
Learn how dog coat color genetics works and predict puppy colors with a Punnett square. Covers the B and E loci, black, chocolate, and yellow Labradors, and epistasis.
16 min read
Genetics
Effective Population Size (Ne) Explained Simply
Effective population size (Ne) is the size of an ideal population that drifts at the same rate as a real one. Learn the formulas, the Ne/N ratio, and the 50/500 rule with data.
16 min read
Genetics
Eye Color Punnett Square: Brown-Eyed Parents, Blue Child?
Can two brown-eyed parents have a blue-eyed child? Yes. Learn how eye color genetics really works, why the simple Punnett square model is wrong, and how to use it anyway.
16 min read
Genetics
Founder Effect: Definition, Causes, and Examples
The founder effect is the loss of genetic variation when a few individuals start a new population. Learn its causes, real examples like the Amish, and how it differs from a bottleneck.
15 min read
Genetics
Fst in Human Populations and Ancestry
What Fst reveals about human genetic variation: the 85% within-populations finding, continental Fst values, ancestry, clines, and what the science does and does not support.
16 min read
Genetics
Fst Values Explained: What Counts as High or Low?
What is a high or low Fst value? See Wright's benchmark bands, real Fst figures for humans and other species, and why the same number can mean different things.
16 min read
Genetics
Fst vs Gst vs Jost's D: Differentiation Measures
Fst, Gst, Hedrick's G'st, and Jost's D all measure population differentiation differently. Here is what each one captures, when they disagree, and which to use.
16 min read
Genetics
Genetic Differentiation and Gene Flow Explained
Gene flow and genetic drift pull in opposite directions to set how differentiated populations become. Learn the Fst-migration link, isolation by distance, and what it reveals.
15 min read
Genetics
Genetic Drift in Conservation and Small Populations
Genetic drift threatens small populations through lost diversity, inbreeding, and the extinction vortex. See how conservation fights back, with the Florida panther data.
16 min read
Genetics
Genetic Drift Practice Problems With Answers
Graded genetic drift practice problems with full worked answers: fixation probability, heterozygosity loss, effective population size, founder effect, and drift versus selection.
16 min read
Genetics
Genetic Drift vs Natural Selection: Differences
Genetic drift vs natural selection compared: random vs directional, fitness vs chance, and population size effects, with a clear table, real examples, and data.
16 min read
Genetics
Genotype vs Phenotype: What's the Difference?
Genotype is an organism's genetic code; phenotype is its observable traits. Learn how they differ, how genes shape traits, and why the same genotype can vary.
14 min read
Genetics
Hardy-Weinberg for AP Biology: Exam Guide
Hardy-Weinberg for AP Biology: the equations on the formula sheet, how to solve FRQ and MCQ problems, the five conditions, common mistakes, and exam strategy.
16 min read
Genetics
The 5 Assumptions of Hardy-Weinberg Equilibrium
The five assumptions of Hardy-Weinberg equilibrium explained: large population, random mating, no mutation, no migration, no selection, and what violating each one does.
16 min read
Genetics
Carrier Frequency: Hardy-Weinberg & the 2pq Step
How to calculate carrier frequency with Hardy-Weinberg. The 2pq step explained, why carriers outnumber affected people, and worked examples for CF, PKU, and sickle cell.
15 min read
Genetics
Testing Hardy-Weinberg Equilibrium With Chi-Square
How to test for Hardy-Weinberg equilibrium with a chi-square test: calculating expected counts, the chi-square statistic, and why degrees of freedom is 1, not 2.
16 min read
Genetics
Hardy-Weinberg Equilibrium Examples (Real Cases)
Real Hardy-Weinberg equilibrium examples: sickle cell and malaria, cystic fibrosis, PKU, the MN blood group, and the cheetah bottleneck, showing where the model fits and fails.
15 min read
Genetics
Hardy-Weinberg for IB Biology (HL Guide)
Hardy-Weinberg for IB Biology HL: deriving the equation, calculating allele, genotype and phenotype frequencies, the assumptions, and how it appears in exams and the IA.
16 min read
Genetics
Hardy-Weinberg Practice Problems With Answers
Graded Hardy-Weinberg practice problems with full worked answers, from allele frequencies and carrier calculations to the chi-square equilibrium test and multiple alleles.
16 min read
Genetics
Homozygous vs Heterozygous: How to Tell Them Apart
Homozygous means two identical alleles; heterozygous means two different alleles. Learn how to tell them apart, why looks can deceive, and what carriers are.
17 min read
Genetics
How to Calculate Fst: Formula and Worked Example
A step-by-step guide to calculating Fst, with a full worked example using Nei's heterozygosity method, plus how Wright's, Weir and Cockerham's, and Hudson's estimators differ.
16 min read
Genetics
How to Calculate the Inbreeding Coefficient
Calculate the inbreeding coefficient F with Wright's path method: find common ancestors, trace the loops, and sum (1/2) to the power of each loop's length. Worked examples included.
15 min read
Genetics
How to Do a Punnett Square: A Step-by-Step Guide
Learn how to do a Punnett square step by step. Find parent genotypes, work out gametes, fill the grid, and read the ratios, with clear worked examples.
6 min read
Genetics
How to Find Gametes From a Genotype (AaBb Method)
Learn how to find the gametes from any genotype. The FOIL method for AaBb, the 2^n rule for counting gametes, worked examples, and the mistakes to avoid.
16 min read
Genetics
How to Use the Hardy-Weinberg Equation (Steps)
A step-by-step guide to using the Hardy-Weinberg equation. Start with q2, find q, then p, then p2 and 2pq, with worked examples and the always-start-with-q2 rule.
16 min read
Genetics
Human Trait Punnett Squares: Tongue Rolling & More
Punnett squares for classic human traits like tongue rolling, earlobes, and widow's peak, plus the honest truth: most are genetic myths, not simple Mendelian traits.
16 min read
Genetics
IB Biology Genetics: Punnett Squares & Crosses
IB Biology genetics made clear: correct allele notation, monohybrid and dihybrid crosses, codominance, sex linkage, and the chi-square test for linked genes.
15 min read
Genetics
Inbreeding Coefficient in Conservation and Breeding
How the inbreeding coefficient (COI) guides real decisions: dog and livestock breeding thresholds, endangered-species studbooks, and managing genetic diversity in small populations.
13 min read
Genetics
Inbreeding Coefficient from a Pedigree
How to read the inbreeding coefficient off a family tree: spot the consanguinity loop, identify common ancestors, and calculate F directly from pedigree symbols.
10 min read
Genetics
Inbreeding Depression Explained
Inbreeding depression is the drop in fitness, survival, and fertility in inbred individuals. Learn why it happens, the genetics behind it, and how it shapes breeding and conservation.
14 min read
Genetics
Incomplete Dominance vs Codominance Explained
Incomplete dominance blends two alleles into one trait; codominance shows both at once. Learn the difference, with snapdragon, blood type, and roan examples.
16 min read
Genetics
Monohybrid Cross: How to Get the 3:1 and 1:2:1 Ratios
A monohybrid cross gives a 3:1 phenotype and 1:2:1 genotype ratio. Learn where these ratios come from and how to work them out, with Mendel's pea examples.
13 min read
Genetics
Population Bottleneck and Genetic Diversity Loss
A population bottleneck is a sharp drop in population size that slashes genetic diversity. See real examples like the northern elephant seal and cheetah, with data and statistics.
16 min read
Genetics
Punnett Square vs Pedigree Chart vs Probability
Punnett square vs pedigree chart vs probability method: what each genetics tool does, when to use it, and how they work together to predict and trace inheritance.
16 min read
Genetics
Punnett Squares for GCSE Biology (AQA, Edexcel, OCR)
Master Punnett squares for GCSE Biology. Exam technique, the mark-scheme method, board differences for AQA, Edexcel and OCR, plus worked questions and common mistakes.
16 min read
Genetics
Genetic Disorders and Punnett Squares: Disease Risk
How Punnett squares predict genetic disorder risk. Covers autosomal recessive (cystic fibrosis), autosomal dominant (Huntington's), and X-linked patterns with clear odds.
15 min read
Genetics
Punnett Square Practice Problems With Answers
Graded Punnett square practice problems with full worked answers, from easy monohybrid crosses to dihybrid, codominance, sex-linked, and blood type questions.
16 min read
Genetics
What Disrupts Hardy-Weinberg Equilibrium?
What disrupts Hardy-Weinberg equilibrium: the five forces of mutation, gene flow, genetic drift, non-random mating, and natural selection, with real-world examples.
15 min read
Genetics
What Is a Punnett Square? Definition, Diagram, and How to Read One
A Punnett square is a grid that predicts offspring genotypes and phenotypes from a genetic cross. Learn its parts, history, and how to read one, with examples.
7 min read
Genetics
What Is Fst? Population Differentiation Explained
Fst measures how genetically different populations are, on a scale from 0 to 1. Learn what it means, where it came from, and how to read it, with the science behind it.
16 min read
Genetics
What Is Genetic Drift? Definition and Examples
Genetic drift is the random change in allele frequencies in a population over time. Learn its causes, real examples, the founder effect, bottlenecks, and why it matters.
16 min read
Genetics
What Is Hardy-Weinberg Equilibrium? Explained
Hardy-Weinberg equilibrium explained: the p + q = 1 and p2 + 2pq + q2 = 1 equations, what they mean, the conditions required, and why it is genetics' null model.
15 min read
Genetics
What Is the Inbreeding Coefficient? (F Explained)
The inbreeding coefficient (F) is the probability that an individual's two alleles at a gene are identical by descent. Here is what F means, how it scales, and why it matters.
10 min read
Genetics
Why Recessive Traits Don't Disappear (Explained)
Why don't recessive traits disappear? Because dominance is not frequency, recessive alleles hide in carriers, and Hardy-Weinberg shows allele frequencies stay constant.
16 min read
Genetics
Dihybrid Cross: Forked-Line Method vs Punnett Square
Compare the forked-line method, the 16-box Punnett square, and the probability method for dihybrid crosses. Learn which is fastest and when to use each one.
16 min read
Genetics
Multiple Alleles Explained: Examples and Genetics
Multiple alleles means a gene has three or more versions in a population. Learn how dominance hierarchies work, with ABO blood type, rabbit coat, and fly eye examples.
16 min read
Genetics
Sex-Linked Traits: How to Do X-Linked Punnett Squares
Learn how sex-linked inheritance works and how to build X-linked Punnett squares for colorblindness and hemophilia, including carrier mothers and why males are affected more.
16 min read