Will your strongest genetic traits always be passed on to your baby? Will she look like you or more like your partner? And can features ‘skip’ a generation?
“It’s impossible to predict how your child will look, because nothing’s straightforward in genetics,” says human genetics expert Professor Bryan Sykes, founder of the DNA analysis service, Oxford Ancestors, and author of The Seven Daughters of Eve: The Science That Reveals Our Genetic Ancestry (WW Norton). “The rules are complex and even when members of a family look alike, we don’t know why. Obviously, certain genes are expressing themselves in a dominant way, but we still don’t understand exactly how.”
Pauline, 34, hoped that her first baby, Isabelle, now 16 months, would look like her, but says that partner James’s genes were hard at work. “Isabelle’s the image of James, but I’m taking the stance that she’ll have my personality! She’s also changing as she grows, so perhaps one day she’ll look more like me.”
How do genes work?
“We inherit two copies of every gene from our parents: one copy from mum, one from dad. The way these copies interact determines how a child will look, but there are so many genes involved – which can also skip generations – that surprises are often in store,” explains human genetics expert Professor Sykes.
Mum of eight Linda, 41, was shocked when two of her daughters were born with striking red hair. “Although my husband, Barry, and I both have very dark hair, Eloise, 6, and Imogen, 2, have ginger hair. We traced this back to Barry’s late aunt, but her hair is the only trait they’ve inherited.”
Lucy, 33, has also witnessed genes skipping a generation. Lucy’s son Louis, 15 months, looks exactly like her mother-in-law. “My husband, Dan, and I both have brown hair and eyes, but Louis has wonderful grey-blue eyes and a mop of blonde hair. My mother-in-law has the same colouring, shape of face and smile. She’s got a gorgeous photo of herself aged 4, and we can really see the resemblance.”
How do genes affect eye colour?
Professor Sykes says that although genetics is far from an exact science, there are certain rules of thumb, particularly with eye colour.
“The gene for brown eyes is usually dominant, which means that if one of the two eye-colour genes you inherit from your parents is brown, that’s the colour your eyes will be. If your child has blue eyes, it’s likely that both eye-colour genes were blue, although there are exceptions.”
How do genes affect skin colour?
The exact genetic determination of human skin colour remains a mystery, even to experts.
The pigment, melanin, passed on to your baby by you, determines skin tone. In the same way she inherits your hair colour, the amount and type of melanin passed on to your baby is determined by a number of genes (approximately six), with one copy of each inherited from her father and one from her mother.
If you’re a mixed-race couple, your baby receives half of each parent’s skin-colour genes randomly, so she’ll usually inherit a blend of both of you. As genes are passed on randomly, it’s impossible to predict what your baby’s skin colour will be. She can appear anywhere in between or, occasionally, outside you and your partner’s traits.
Also, if you’re a mixed-race couple and your child is born with very dark skin, a sibling or even non-identical twin, could be born with a very different skin tone altogether.
“The blue eyes were a bit of a shock!”
“Morgan was fairer than we expected at birth. People looked at her dad, Delroy, who’s black, and did a double take. Isabella looks like Delroy, but is like me in mannerisms. We didn’t know what to expect when Mabel-Jane arrived, but certainly not fair skin and blue eyes – that was a bit of a shock!”
Natalie, 36, and husband, Delroy, parents to Morgan, 14, Isabella, 11, and Mabel-Jane, 3
“People assume our boys are twins”
“When I got pregnant for the second time, I was excited to see how different my new baby would look and was amazed by how similar he was to Ezra (my first child). As he got older, the similarity became uncanny – lots of people assume they’re twins. Ezra’s short for his age and Seth started walking at 9 months. People are often shocked when Ezra starts a conversation and Seth is babbling – they think Ezra’s a genius!”
Leanne, 32, and husband, John, parents to, Ezra, 3, and Seth, 16 months
“No one ever guesses they’re twins”
“I’m half Brazilian and have very dark skin and hair, whereas my husband Steve’s fair. Scarlett looks like a mixture, so we expected the twins, Sasha and Alex, to be the same. But Alex is fair like his dad, while Sasha is dark like me. No one ever suspects they’re twins unless we tell them. They really are like mini-versions of us, in character and looks, which is lovely. Alex is laid-back like Steve, while Sasha has my feisty temperament.”
Anna, 42, and husband Steve, parents to Scarlett, 6, and twins Sasha and Alex, 2