Two brothers, one genetically enhanced, share the same DNA.
Now they hope their genetic experiments will help one brother overcome a serious illness.
They are the first two siblings to share their genes with a twin, the first of whom was born with a serious heart condition.
Dr Sarah Maughan, who has led the research for the Royal College of Surgeons of Ireland, said it was rare to see twins who were born with the same condition.
“I was so excited to be able to share my brother with my twin sister.
It was a very big moment for both of us,” she said.”
It has been very, very hard work and there are many challenges and setbacks.”
However, I am very confident we have achieved something special.
“There is still a lot of work to be done before we are able to be in a position to actually have a successful genetic enhancement for a disease that is so debilitating.”
Hopefully this will inspire people to try to have their own twin.
“We have both had a serious medical condition which has left us with very limited mobility, but we are both very strong and we have managed to cope.”
A genetic test could help a brother who suffers from a rare disease who has no hope of living a normal life with his twin sister, Sarah M. Maughon, a surgeon at the Royal Free Hospital, said: “I can’t wait to see how this is going to go.”
You would be amazed how far you can go, with the technology available.
“But there is still so much more to do, so this is something that is only just starting to be explored.”
The researchers were studying two identical twins, both born with congenital heart defects, and were hoping to find genetic clues to how one affected the other.
The brothers were born on the same day in 1987, in a similar circumstances.
They had the same parents and the same grandparents.
They were both diagnosed with congenitally rare genetic conditions.
The twins share the genetic code but differ in that one of them is an extra copy of a gene called the FOXP2 gene.
This gene is the most common in humans, and is also found in dogs and mice.
It is expressed in a variety of cells including the heart, blood vessels and muscle cells, and in the brain and other body parts.
The gene also has an extra version that is turned on in some people who have a rare genetic condition called microcephaly.
This is an abnormality where babies are born with abnormally small heads.
In one of the brothers, a gene in the FOXp2 gene is activated, causing the other twin to have abnormally large heads.
The researchers discovered that the twin that was born without a heart defect also had a microcephalic heart condition called trisomy 13, which causes babies with the condition to be born with unusually small heads and a brain abnormality called microencephaly, which makes it difficult for them to talk and move their arms.
In their study, Dr Maughman and her colleagues studied the genes of the twin who had the microcephephalic condition.
The study was published in the journal Nature Genetics.
The research was funded by the Wellcome Trust.