'Brother having baby with hubby's sis so I'll get to see how my kid would look'

01 December 2023 , 10:52

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'Brother having baby with hubby's sis so I'll get to see how my kid would look'

A woman was given a huge surprise when she found out that not only was she going to be an aunty – the baby could give her an idea of how her own child would look.

Mack Topa, 26, filmed the moment she was given a box to open which revealed her brother is soon to have a baby with her husband's sister. She is seen in the TikTok video – which has been viewed more than 385k times – being given the box while her brother, husband and the mother-to-be look on.

She quips that she "thought there was a dead bird" then asks if she's going to cry, before opening it and after a slight pause, squeals in delight, before hugging the expectant parents and her hubby. The social media manager and content creator from Ottawa, Canada, said that the unusual situation came with one big upside – she's going to get to see what her baby might potentially look like too.

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The aunty-to-be is delighted by the news

Mack Topa is at first surprised about the news of the baby

The 26-year-old said: "It was shocking to find out that my brother is having a baby with my husband's sister. It will technically have the same genes as my husband and I, so we get to see what our baby would potentially look like."

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And other users of the social media site said they were delighted for her and shared their own stories, with one saying: "We have this in my family. My dad’s sister is married to my mum’s brother – their eight kids are my double cousins. Blood related equals half siblings. 25 percent," while another said: "This is cool. My grandparents and great uncle/aunt did the same thing and it was fun growing up with a bunch of double cousins."

However, how the baby actually looks is down to chance and very much the way the family's genes interact, according to Dr Barry Starr, writing on Ask a Geneticist at The Tech Interactive: "The kids would end up being about twice as related as regular first cousins (who share 12.5 percent DNA). And at 25 percent shared DNA, that would make them about as related as half siblings. Keep in mind that this is only on average. The true amount of shared DNA may be a bit higher or lower, mostly due to random chance and how DNA is inherited."

So can Ms Topa have an idea about what her child's hair will look like? Will they have blue eyes or brown eyes? Parents will always make predictions, but they can never be 100 percent sure until the baby is born. Dr Starr told Parents.com: "If we examined all a fetus' DNA, we still wouldn't be able to truly anticipate things. So much is unknown about genes."

And he added that with the hair, it is dependent on what genes have been passed on and which are the stronger. For instance, if two brunette parents produce a blonde baby, that means both parents carry recessive blonde genes among their dominant brown ones, but only their light-coloured genes were passed on. He said: "When sperm met egg the right mix of genes popped up so it could be expressed."

With the eyes, at least two genes influence the eye shade that develops, unless a baby's eyes are very dark at birth, they will typically change. And it can take at least six months before eye colour holds fast. "The colour-producing cells in the iris need exposure to light to activate," said Dr Starr. And as to their looks, sometimes children end up looking exactly like one parent, or even closely mirroring a sibling, and sometimes they don't resemble anyone in the family.

Paul Donald