Genetics 101: Visualizing Inheritance
Ever wondered how traits are passed down through generations? This advanced calculator uses a classic genetic tool called a Punnett Square to visually demonstrate how alleles from each parent can combine to produce different outcomes in their offspring.
Genotype vs. Phenotype
Before diving in, it's helpful to know two key terms:
- Genotype: This is the specific genetic makeup, or set of alleles, an individual has for a trait (e.g., DD, Dd, or dd).
- Phenotype: This is the observable physical trait that results from the genotype (e.g., having dimples or not having dimples).
Understanding the Genotype Options
Our calculator lets you specify the exact genotype for each parent, which is crucial for an accurate prediction.
- Homozygous Dominant (e.g., DD): Has two copies of the dominant allele. They will show the dominant trait and will always pass a dominant allele to their child.
- Heterozygous (e.g., Dd): Has one dominant and one recessive allele. They will show the dominant trait but are a "carrier" of the recessive trait, meaning they have a 50% chance of passing on the recessive allele.
- Recessive (e.g., dd): Has two copies of the recessive allele. They will show the recessive trait and will always pass a recessive allele to their child.
How to Read the Punnett Square
The Punnett Square is a simple grid that shows every possible combination of alleles from the parents. One parent's alleles are listed across the top, and the other's are down the side. The four squares in the middle show the possible genotypes for a child, with each square representing a 25% probability. By counting the results, we can accurately predict the chances of a baby inheriting a specific genotype and, in turn, a specific phenotype.
Beyond Simple Genetics
While single-gene traits are perfect for learning the basics, most human characteristics are polygenic, influenced by many genes working together. For fun predictors for specific traits, check out our Baby Eye Color Calculator, Baby Hair Color Calculator, and the basic Baby Traits Calculator.