We have probably already gene-edited babies to have better brains.

The controversial gene editing performed on a pair of twins in China when they were embryos may have unintentionally supercharged their brains, scientists suggest.

In November, Dr He Jiankui and a team of Chinese scientists announced that they had used the experimental gene-editing method, CRISPR to alter the genome of twin embryos that had already been born, twin girls Lulu and Nana.

The team used the procedure to suppress a gene called CCR5, which allows the HIV virus to sneak into some human cells. Gene editing was performed on Lulu and Nana to protect them from inheriting their father's HIV, Dr He said.

But every day we learn more about what the over 25,000 genes in human DNA do.

And today, a study published in the journal Cell found that suppressing CCR5 also has effects on memory and cognitive function.

Chinese scientists, led by Dr He Jankui used CRISPR to edit the DNA of a pair of embryos to prevent HIV. Changes made to the twin girls, born in November, likely enhanced their brains

The University of California, Los Angeles (UCLA), study was only looking at stroke victims, but the implications for the gene-edited twins are massive, its authors say.

They predict that Lulu and Nana's genes were changed in a way that will not only protect them, but will improve their mental performances.

The sudden announcement that two gene-edited babies had already been born shocked the scientific community and the world over.

It was a world-first that brought with it ethical outcry and concern over the prospect of 'designer babies.'

The Chinese scientists insisted that they had only used CRISPR to prevent disease - HIV - and not to make any more arbitrary changes or improvements to the fetuses.

But, intentionally or unintentionally, that turns out not to be the case.

Years ago, Dr Alcino Silva and his neuroscience lab at UCLA were looking for a way to treat cognitive deficits.

They investigated many genes and stumbled onto CCR5. The gene looked like a promising target for alterations that could improve memory and learning, or at least help people with impairments to those cognitive functions.

When Dr Silva and his team looked up CCR5 he was shocked to find it is the same gene that, when expressed, allows the HIV virus access to human cells.

And in a happier twist, there was already an HIV drug that turned off the gene to deny the virus access to cells. It looked as though suppressing the gene might help improve cognition, too.

It's really scary, because once a mutation is introduced into the human population, it's really hard to get rid of it Dr Alcino Silva, University of California, Los Angeles neuroscientist

He and his team found that changing CCR5 in mice caused 'a variety of changes in the brain of these animals and their biochemistry and cell-to-cell communications,' Dr Silva told DailyMail.com.

They reported the exciting discover in a 2016 journal article, and decided to see if their gene knockdown could improve recovery from brain injuries.

On Thursday, they published the results of their new study, which suggested people without or with low levels of the CCR5 gene recover their memories and cognition more easily after strokes and that when the gene was suppressed with a drug in mice, they too had better memory and cognition.

The bottom line: 'If you change CCR5, you change the brain. You change learning and memory,' said Dr Silva.

'There's so much similarity between the brains of mice and humans, that it would be safe to assume that [Lulu and Nana's] brains have definitely been changed.'

Many members of the Ashkenazi Jewish population naturally have this deletion - and appear to have enhanced learning and memory compared to people with the gene.

It won't be possible to tell clearly if or to what extent, exactly Lulu and Nana's brains have been changed, since we won't know what they would have been like otherwise.

The brain functionality involved in recovering from stroke is a form of neuroplasticity that the surviving parts of the brain need in order to learn and remember how to do tasks that now-dead parts of the brain did before.

Relearning in this way is very similar to more generalized learning and memory, so the twins might have some distinct advantages - or not.

'They may not be better at all things, they may be better at some things than others - we just don't know,' Dr Silva says.

'And that's the danger,' he adds, comparing the laundry list of unknowns that come with gene-editing to 'Pandora's Box.'

For example, the vague idea of enhanced memory sounds great, but it might not be.

What's not black and white and is extremely dangerous is when we have normal individuals that we are trying to enhance in one way or another - that's extremely arrogant. Dr Alcino Silva

'The brain spends a great deal of energy forgetting. It's one of its most important functions,' says Dr Silva.

'Most things we perceive around the world we actually want to forget because they stand in the way of us learning and going about our lives. [Those unnecessary things] are like noise in hour heads.'

So if Lulu and Nana are indeed gene-edited to remember more, it might actually cause them more problems than it solves.

With gene-editing, 'you're going to indirectly intervene on one thing, 10 things, a thousand things that you never meant to intervene on,' says Dr Silva.

And each of those small, inadvertent changes has echoes beyond the individuals they are made in.

'It's really scary, because once a mutation is introduced into the human population, it's really hard to get rid of it,' says Dr Silva.

'Look at what we've done to the environment. Even small changes have consequences we can't predict.'

Gene editing holds incredible promise to treat and even eradicate disease, but we have to be careful about where we draw the line between treating problems and creating new ones, because we simply don't know enough.

'The ethics, I think, are black and white if people are suffering. We can intervene in people that have a serious disorder that is life-threatening or profoundly effects their lives, then there is an ethical obligation to do anything we can to help them,' says Dr Silva.

'What's not black and white and is extremely dangerous is when we have normal individuals that we are trying to enhance in one way or another - that's extremely arrogant.

'We can barely help the people that have problems, let alone the ones that don't, and I just hope that people that have the power to make these decisions as to when we should intervene and reshape the human genome, I hope they pause and think about all the foolish things we have don in the past' and their unintended consequences.'