If blue eyes are a recessive gene and green eyes are a dominant gene, why are there more people with blue eyes?
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Brown is more dominant over green and blue, green is dominant over blue, and blue is recessive. Recessive genes require two of the recessive genes in order to exhibit the trait (bb). That means a blue-eyed parent is 100% guaranteed to pass on the recessive gene for blue eyes. Whereas a parent exhibiting a dominate trait can have many different combinations (BB Bb BG) for brown and (GG Gb) for green. Since each parent can only pass down 1 gene each to their child, you can see a trend. A brown-eyed parent has a 66% chance to pass on the brown gene, a 16% chance blue, and 16% green. A green eyed parent has a 75% chance to pass on the green gene and a 25% chance to pass on the blue. But, again, a blue-eyed parent has a 100% chance to pass on the blue gene because the blue gene is all they have. So, really, because green is less dominant than brown AND harder to pass on than blue, you find it less commonly. What you’d have to do to prove it is make a chart and match up all the possibilities to see what the results would be. Thankfully, this has already been done, and I can link you a nice visual of the results.
https://www.johnoconnor.co.nz/wp-content/uploads/2018/08/eye-colour-gene-chart.png
TL;DR Brown genes dominate green and blue genes, green genes dominate blue genes, and blue genes are easier to pass on than green genes. When you consider all 3 possibilities, green is mathematically less likely.
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