The truth is quite scientific, as you might expect. It’s all determined by the level of melanin in our irises (the coloured part of the eye around the outside of the pupil).
Most Caucasian babies are born with blue eyes yet only one in six will retain blue eyes as adults!
What is Melanin?
Melanin is made up of melanocytes which form brown coloured pigment. This is what causes your eye colour to change – the more melanocytes you have, the darker your eyes will be! This means that light eye colours have low melanin levels and dark eye colours have much higher melanin levels.
How are our melanin levels determined?
This is where genetics come into play! Melanin levels are determined by two main genes; the OCA2 Gene and the HERC2 Gene.
OCA2 – This gene produces P Protein that determines the amount of melanin present in the iris.
HERC2 – This gene limits the OCA2 gene leading to less melanin in the iris and lighter eye colour.
Therefore, less P Protein would be the reason for having blue eyes rather than brown eyes.