But she and partner Selwyn Clapp had been there before, and they could do this again.

The genetic syndrome that saw the mother-of-three needing an invasive schedule of surgery up until her teenage years to correct the shape of her skull was passed on to her twins, Benjamin and Spencer.

And now, almost two years on, their third son Chester looked just like his mum when he emerged kicking and screaming into the world.

“It’s meant to be a 50-50 chance of passing it on, but at the moment it’s feeling a lot more like 100-100,” Ms Hocking said.

“But whether we find out when I’m pregnant or after they’re born, it wouldn’t change anything.

“You wouldn’t have thought it was possible to love someone so much.

“We had the twins and adore them. Would we have enough love for another baby?

“The moment Chester was born he was perfect and I feel in love all over again.”

Craniofacial surgery is vital to stop the growing brain from being compressed in a skull that is too small. Without treatment, it can be fatal.

But surgical techniques have advanced dramatically, so her boys look likely to need just one operation as babies.

“It’s hard every time they come back and say they do have it, because I’m the carrier,” Ms Hocking said.

“It’s difficult knowing you’re passing this gene on to your kids. But we wouldn’t change a thing because it’s fixable. It’s all cosmetic. It doesn’t impair their learning, their development or growth.”

In March last year, in a specially organised back-to-back full day of surgery, the couple handed their eight-month-old twins to plastic surgeon Jonathan Burge and neurosurgeon Alison Wray for the corrective operation.

The posterior distraction surgery is typically performed on babies, before the sutures have fused on the skull and while the bones are still soft.

The Royal Children’s Hospital has recently started using the technique — increasing the size of the skull by lengthening the head from the back — in children up to eight years of age

“It’s our get-out-of-jail card for making the space bigger for that rapidly growing brain,” Mr Burge said.

“It gives us time, which you urgently need in those first few years of life.”

In the operation on June 26, once Ms Wray cut the skull from across the top of the head from ear to ear, Mr Burge attached distractors to the skull with plates and screws.

The arms of the distractors stick out from Chester’s temples like antennas.

Each day the couple turns the distractors twice to open the gap by .3mm. These turns mimic the kind of pulsing the skull bones need to grow and strengthen.

Just as surgeons did for the twins, they saved a bag of hair clippings from Chester’s first haircut — the shaved runway across the top of the head where the surgeon’s scalpel would make its incision.

Two days after surgery, Chester was discharged. His trademark smile and poked-out tongue were back.

The twins were back to running down to Chester’s bedroom, yelling his name and smothering him in kisses.

“Chester will be the one who gets the twins in trouble,” Ms Hocking said.

Words Brigid O’Connell, Herald Sun.  Photos Jay Town & Jake Nowakowski, Herald Sun.