Two parents with blue eyes can't have a baby with brown eyes and other gene myths busted

Why do we look the way we do? [Photo: Getty]

From the colour of your hair to that weird little toe that curls under, you probably assume your characteristics are inherited from your parents, and you’d be right.

But, there are still a few mysteries about our genetic make-up.

For example, why you’ve got blue eyes even though your parents both have brown and why you’re left-handed when your mum and dad both favour their right?

It’s all to do with your genes.

Your genes carry information that makes you who you are and what you look like and they are passed onto you, or inherited from your parents.

Experts believe there are 60,000 to 100,000 genes (made up of DNA) in a human being's 46 chromosomes.

A baby inherits 23 chromosomes from his mother and 23 from his father.

The science of genetics is undeniably complicated, and experts are always discovering new information about what determines our looks and personality, but there are some hereditary myths that we are able to bust.

Your eye colour

You might think there are just three different eye colours - brown, blue and green - but in reality our eyes come in a whole spectrum of different shades made up of these colours.

Eye colour is directly determined by the amount of melanin, or brown pigment, in the iris, and this is determined by a combination of genes because eye colour is a polygenic trait.

In the past scientists used to think that eye colour was determined by a single gene and followed a simple inheritance pattern in which brown eyes were dominant to blue eyes.

But according to more recent research, the eye colour inheritance is more complicated than originally suspected because multiple genes are involved.

A common myth is that parents who both have blue eyes cannot have a child with brown eyes because of dominant and recessive genes, but in reality genetic variations sometimes produce unexpected results.

Though there is a less than 1% chance of blue-eyed parents having a brown-eyed child, it is not out of the question.

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Eye colour is inherited but it's complicated [Photo: Getty]

Your handedness

It’s easy to chalk the hand you prefer to use down to genetics, but in reality handedness seems to be influenced by multiple factors, including external factors (such as culture and parental pressure) and chance.

Scientists initially thought that one single gene determined the hand you preferred to use, but more recent studies have suggested that multiple genes are at play.

Like many other complicated traits, handedness does not have a simple pattern of inheritance.

While it is fair to say children of left-handed parents are statistically more likely to be left-handed than children of right-handed parents, because the overall chance of being left-handed is relatively low (just 15% of the population is left-handed), most children of left-handed parents are also right-handed.

Hair colour

Like our eye colour, hair colour is actually determined by the amount of a pigment called melanin within our hair.

According to research an abundance of one type of melanin, called eumelanin, gives people black or brown hair, while an abundance of another pigment, called pheomelanin, gives people red hair.

The type and amount of melanin in hair is determined by many genes, but science is still piecing together the information about it all.

Within the whole spectrum of potential hair hues, dark hair is most common, with more than 90 percent of people worldwide having brown or black hair. That’s followed by blonde hair.

Red hair, occurs in just 1 to 2% of the population.

Your hair colour basically boils down to the particular genes you inherit from your parents. If your parents both have brown hair, there’s a good chance you will too, but not always.

Again it comes down to the battle between dominant and recessive gens. Brown hair is the more dominant gene, which is why that’s the most common natural hair colour.

But parents can be carriers of recessive genes. While they may have brown hair, they could have a recessive gene for red hair and could pass this onto their child if it mixes with a red gene from the other parent.

So two brown haired parents could still have a child with bright, red hair.

Hair loss is thought to be partially down to your genes too. If your grandfather and father went bald at an early age, the strong baldness gene means you could be more likely to shed your hair young too.

READ MORE: Science says your mum is to blame if you have bad relationships

Left handedness is in the genes [Photo: Getty]

Other characteristics

Ever wondered why you’ve got a little dimple on your shoulder or you and your mum have the same odd shaped big toe, it probably is inherited.

According to studies dimples are enormously heritable, meaning that people who have dimples tend to have children with dimples, but that’s not always the case.

Mainly because dimples are considered an ‘irregular’ dominant trait, meaning their their inheritance isn't completely predictable.

And dimples aren’t alone in potentially being passed down. Certain other characteristics such as having a widow’s peak or having one eyebrow higher than the other are believed, by experts, to be dominant.

The shape and size of your fingers and even your toenail shape, also often seem to be inherited through generations.

Crooked teeth? That could have been inherited too. Just like your eye colour, the shape and size of your mouth and jaw, are genetically determined.

Scientists believe they have even identified a specific gene which they believe could determine whether people with a gap in their teeth will go on to have children with the same. And researchers believe this gene is dominant.