Meet the expert: Dr Judith Virjee is a consultant physician who studied molecular genetics and biochemistry.
Nothing can replace the excitement of meeting your newborn for the very first time. But while you’re counting down the days until the birth of your new baby, it’s fun to speculate just what your baby will look like. Will she have your eyes? Your chin? Your partner’s curly hair? While there are no certainties when it comes to babies, you can work out the probability of her inheriting particular characteristics from you and your partner.
It’s all in the genes, you see. Genes are tiny instructions that decide what we look like. Half come from you, half from Daddy.
Some characteristics, like eye and hair colour, are controlled by a single pair of genes, called alleles. An allele can either be dominant or recessive – and the dominant allele will always win the battle over the recessive allele, and determine the outcome.
Dark hair is a dominant allele, but blond hair is a recessive allele. So if you and your partner both have dark hair, and pass on those dominant genes, you are likely to have a child with dark hair. If you pass on that dominant gene and your partner passes on a recessive gene for blond hair, your baby will still have dark hair, as it is more dominant. But if you both pass on a recessive gene for blond hair, your baby will have blond hair – even though you both have dark.
And this is why you can only speculate!
And this is why you can only speculate! You or your partner might not have a certain trait, but it doesn’t mean you don’t carry the allele for it. Genes can remain recessive for many generations. Look at photos of grandparents and great-grandparents for clues of recessive alleles that might be lurking in your genes.
Straight or curly hair
If you have curly hair, chances are your baby will too. Curly is the dominant allele over straight hair, so if you inherited your grandma’s corkscrew locks, you’ll probably pass that gene on to your child. If you and your partner have poker-straight hair, then your baby has a high chance of inheriting the same.
Brown eyes are a dominant trait and blue eyes are recessive. If you and your partner each carry two brown-eyed genes, you’ll have a brown-eyed baby. If both of you have a blue-eyed recessive gene, there’s a one-in-four chance your baby will have blue eyes. Other factors can also influence eye colour, such as the amount of melanin your body produces, which can result in green or hazel eyes.
Some people have the ability to bend their thumbs right back towards their hands, which means they carry the dominant allele. If you do not have double-jointed thumbs, then you have the recessive allele, and your baby is unlikely to inherit the trait unless your partner has the ability.
Do you have the trademark V-shape in your hairline, in the middle of your forehead, known as a widow’s peak? This is a dominant trait.
Dark hair is a dominant allele with blond hair recessive. Red hair is a more complicated story but, put very simply, it also falls into the recessive allele. So if you have brown hair but carry a recessive gene for red hair, and your partner does too, there’s a 25 per cent chance your newborn will have red hair.
Dimples are a dominant trait, so if both you and your partner have this strong physical feature, then your baby is three times more likely to as well. Aww!
Round or oval shapes are the dominant allele, while a square shape is recessive.
A cleft or ‘dimple’ chin is an inherited trait and a dominant allele.
Freckles are usually found on fair-haired, light-skinned people and are a dominant trait.