body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background-color: #f9f9f9;
}
.calculator-wrapper {
background: #ffffff;
padding: 30px;
border-radius: 12px;
box-shadow: 0 4px 15px rgba(0,0,0,0.1);
margin-bottom: 40px;
border-top: 5px solid #4a90e2;
}
.calc-header {
text-align: center;
margin-bottom: 25px;
}
.calc-header h2 {
margin: 0;
color: #2c3e50;
}
.input-group {
margin-bottom: 20px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #555;
}
.input-group select {
width: 100%;
padding: 12px;
border: 1px solid #ddd;
border-radius: 6px;
font-size: 16px;
background-color: #fff;
cursor: pointer;
}
.input-group select:focus {
border-color: #4a90e2;
outline: none;
}
.calculate-btn {
width: 100%;
padding: 15px;
background-color: #4a90e2;
color: white;
border: none;
border-radius: 6px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background 0.2s;
}
.calculate-btn:hover {
background-color: #357abd;
}
.results-area {
margin-top: 30px;
padding: 20px;
background-color: #f0f7ff;
border-radius: 8px;
display: none;
}
.results-area h3 {
margin-top: 0;
text-align: center;
color: #2c3e50;
}
.color-bar-container {
margin-bottom: 15px;
}
.color-label {
display: flex;
justify-content: space-between;
margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
}
.progress-bg {
background-color: #e0e0e0;
height: 24px;
border-radius: 12px;
overflow: hidden;
}
.progress-fill {
height: 100%;
width: 0%;
transition: width 1s ease-in-out;
display: flex;
align-items: center;
justify-content: flex-end;
padding-right: 10px;
color: white;
font-size: 12px;
font-weight: bold;
}
.fill-brown { background-color: #8D6E63; }
.fill-green { background-color: #81C784; }
.fill-blue { background-color: #64B5F6; }
.article-content {
background: #fff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}
.article-content h2 { color: #2c3e50; margin-top: 30px; }
.article-content h3 { color: #4a90e2; }
.eye-icon { font-size: 24px; vertical-align: middle; margin-right: 10px; }
Understanding Baby Eye Color Genetics
Waiting to see what color eyes your baby will have is one of the most exciting parts of pregnancy and early parenthood. While many babies are born with blue or gray eyes, their permanent eye color is determined by genetics and melanin production, a process that can take up to three years to finalize.
How Eye Color is Determined
Eye color is a physical trait (phenotype) determined by the pairing of genes passed on from both parents. While scientists used to believe that eye color was determined by a single gene, we now know it is a polygenic trait involving at least 16 different genes. However, the two most influential genes are located on Chromosome 15: OCA2 and HERC2.
To understand the prediction model used in the calculator above, it helps to understand the hierarchy of color dominance:
- Brown is the most dominant eye color allele.
- Green is dominant over Blue but recessive to Brown.
- Blue is recessive to both Brown and Green.
The Genetic Combinations
Even though the genetics are complex, we can estimate probabilities based on the parents' visible eye colors (phenotypes). Here is the logic behind the numbers:
Two Blue-Eyed Parents
Because blue is a recessive trait, parents with blue eyes generally carry two blue alleles (bb). Therefore, it is extremely likely (approx. 99%) that their child will also have blue eyes. While rare genetic mutations or modifier genes can result in a green-eyed child, a brown-eyed child is genetically very unlikely in this scenario.
Two Brown-Eyed Parents
This is the most variable scenario. Since Brown is dominant, a parent can have brown eyes with a genotype of either Brown-Brown or Brown-Blue (carrying a recessive blue gene). If both parents carry the recessive blue gene, they have a roughly 25% chance of having a blue-eyed baby, despite both having brown eyes.
One Brown, One Blue
If one parent has brown eyes and the other has blue, the outcome depends heavily on whether the brown-eyed parent is a "carrier" of the blue gene. In general population averages, this results in a roughly 50/50 split between brown and blue eyes, though green is occasionally possible due to modifier genes.
When Does Eye Color Become Permanent?
Many Caucasian babies are born with blue or gray eyes due to a lack of melanin at birth. Melanin is the pigment that darkens skin, hair, and eyes. As the baby develops, melanocytes (pigment-producing cells) react to light and secrete melanin.
If melanocytes secrete a little melanin, the eyes may turn green or hazel. If they secrete a lot of melanin, the eyes will turn brown. This process usually begins rapidly between 6 to 9 months of age, but subtle changes can continue until the child is about 3 years old. Brown-eyed babies typically do not change color, as the pigment is already present at birth.
What About Heterochromia?
In rare cases, a child may have two different colored eyes, or a single eye with multiple colors. This is known as Heterochromia. It can be caused by genetic variations, chimerism, or injury to the eye during delivery. While often benign and simply a unique cosmetic trait, it should always be checked by a pediatrician.
function calculateEyeColor() {
var mom = document.getElementById('momEye').value;
var dad = document.getElementById('dadEye').value;
var resultDiv = document.getElementById('results');
// Initialize probabilities
var probBrown = 0;
var probGreen = 0;
var probBlue = 0;
// Logic based on simplified genetic probability models
// Using var for compatibility as requested
// Scenario 1: Blue + Blue
if (mom === 'blue' && dad === 'blue') {
probBrown = 0;
probGreen = 1;
probBlue = 99;
}
// Scenario 2: Green + Green
else if (mom === 'green' && dad === 'green') {
probBrown = 1; // <1% usually
probGreen = 75;
probBlue = 24;
}
// Scenario 3: Brown + Brown
else if (mom === 'brown' && dad === 'brown') {
probBrown = 75;
probGreen = 18;
probBlue = 7;
}
// Scenario 4: Blue + Green (Order doesn't matter)
else if ((mom === 'blue' && dad === 'green') || (mom === 'green' && dad === 'blue')) {
probBrown = 0;
probGreen = 50;
probBlue = 50;
}
// Scenario 5: Blue + Brown
else if ((mom === 'blue' && dad === 'brown') || (mom === 'brown' && dad === 'blue')) {
probBrown = 50;
probGreen = 0; // Very rare in simplified model, usually flows to Blue/Brown
probBlue = 50;
}
// Scenario 6: Green + Brown
else if ((mom === 'green' && dad === 'brown') || (mom === 'brown' && dad === 'green')) {
probBrown = 50;
probGreen = 37;
probBlue = 13;
}
// Show results container
resultDiv.style.display = 'block';
// Update Text Labels
document.getElementById('label-brown').innerHTML = probBrown + '%';
document.getElementById('label-green').innerHTML = probGreen + '%';
document.getElementById('label-blue').innerHTML = probBlue + '%';
// Update Bar Widths
// Using setTimeout to allow the display:block to render before animating width
setTimeout(function() {
document.getElementById('bar-brown').style.width = probBrown + '%';
document.getElementById('bar-green').style.width = probGreen + '%';
document.getElementById('bar-blue').style.width = probBlue + '%';
}, 50);
}