What Factors Determine Babies’ Eye Colour?

Have you ever wondered what factors determine babies’ eye colour?

It is an interesting topic to read about because, aside from the cliché that eyes are windows to the soul, the eyes and eye colour as the most fascinating part of a baby’s face. At least I think so. If you’re also interested in knowing about eye colour, read on!

What Makes the Eye Colour

The iris, which is the coloured part of the eye, contains the pigmentation that determines the colour of the eyes. The most common eye colours are blue, green, black, brown, and hazel. Sometimes, it can be other pretty hues like grey and amethyst.

A baby’s eye colour is fairly easy to predict when the parents have the same eye colour. There are cases when the offspring has a different eye colour (for example, blue-eyed parents giving birth to a brown-eyed child), but the chances of this happening is only 25%. However, the more interesting case is when the baby’s mother and father have different eye colour. Now what? How do you predict babies’ eye colour in this case? Let’s find out!

Factors that Determine Babies’ Eye Colour

a. Genes

It is the genes, which are made up of alleles, that determine the baby’s physical and mental characteristics and even disposition and temperament. Therefore, it makes sense that genes also play a big part in determining babies’ eye colour.

In grade school, we were taught that genes were either dominant or recessive. Dominant genes usually have higher chances of being passed on, while recessive genes may not appear and is unexpressed. However, recent studies show that genetic determining eye colour is much more complex that weighing dominant and recessive genes. As of 2010, researchers are still developing a much more accurate way of predicting babies’ eye colour.

b. Diffusion of light

Aside from the amount and pattern of melanin, which is greatly characterised by genes, babies’ eye colour is also determined by the iris and how it scatters and diffuses light. Situated between the cornea and the intraocular lens, the iris reflects light and then produces a colour that depends on the amount of pigmentation present.

For example, if there is a lot of melanin or pigmentation and the iris reflects a little amount of light, the iris appears to be dark brown or black in colour. However, if there is a lot of light reflected, the iris can appear to be light brown.

Is it possible to predict eye color?

In school, we’ve been taught the simple “two-genic” genetic model (thanks, Mendeleev) as an exercise to predict eye colour. However, the model is very limited as it only views dominant and recessive characteristics in black and white, making it not entirely reliable.

While it can be used to explain the resulting eye colour of children, and while it can be used to try to predict a future child’s eye colour, it may not produce accurate results.

Can eye colour change?

Yes! But this is probably not the dramatic change that you’re expecting. Just like what we discussed above, eye colour is not only determined by genes and pigmentation but also by how the iris scatters and diffuses light. Among people who have dark pigmentation, their irises may range from dark brown to light brown depending on the light.

As for people of light colour or less pigmentation, the change of eye colour can change more drastically. For example, a person with hazel-coloured eyes may experience changing eye colour depending on the colour of his clothing. This is perfectly normal because the colour of our clothing also affects the colour of light absorbed by the iris.

What else do you want to know about babies’ eye colour?