Timothy Sexton, who has a PhD in population genetics [from the University of British Colombia] and over 18 years of experience with genetic analysis [through his company DNA Romance], told Newsweek: “The development and rarity of green eyes are influenced by intricate genetic interactions and the mixing of human populations.”
According to a study published in late January this year in Scientific Reports, “the most common iris color in the world is brown, accounting for about 79 percent.”
Sexton, the founder of DNA Romance, an online dating platform providing connections based on a DNA test analysis, said green eyes are estimated at 2 percent of the population worldwide. This prevalence is much higher in certain European countries, such as Ireland, Scotland, the U.K., France and Germany, he added.
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[Opthamologist and ophthalmic surgeon Dr. Jovi Boparai, founder and CEO of CorneaCare,] further explained that many babies are born with lighter eye colors, such as blue or gray, because melanin production in the iris is “still ramping up.”Related on the SLP
But as they grow older, typically between six months and three years of age, the iris produces more melanin, “potentially causing the eyes to darken to hazel, brown, or even a deeper shade of green,” he said.
Even beyond infancy, eye color can undergo subtle changes depending on lighting, mood, and even clothing choices. Boparai said: “This is primarily due to the way light interacts with the melanin and other pigments in the iris.” For example, green eyes might appear more blue in certain lighting conditions or slightly hazel in direct sunlight, he said.
