Jayson and Michelle Whitaker had what is believed to be Britain's first genetically-selected baby after receiving the treatment at a Chicago genetics institute.
The new baby, named Jamie, was delivered by Caesarean section on Monday after being genetically matched, while still an IVF embryo, to his four-year-old brother Charlie. Charlie has a rare form of anemia and his parents traveled to the United States for treatment after being refused permission to genetically select a tissue match embryo by the Human Fertilisation and Embryology Authority.
The father, said "All we did was change the odds from a one-in-four chance of a tissue match to a 98 percent chance.
"We are not creating anything new. We are just trying to choose between the embryos to find the one that is normal and can save the life of its sibling.
"There was no selection on the basis of color of eyes or hair or sex."
Charlie has Diamond Blackfan anemia which can only be cured with a transplant of stem cells from a sibling with a perfect tissue match.
"These are not babies brought into the world just to save the sibling's life. These are families who want a healthy child, and if that healthy child can also save the life of the child they already have, I think it is a double blessing.
It is still not certain that Jamie can help his brother. The new born baby is currently undergoing blood tests to see if he has perfect tissue match and the family will have to wait six months to ensure that he is not affected by the same syndrome.
The vital stem cells have already been collected from Jamie's umbilical cord.