Jessica Newell is 13-months-old and has mitochondrial disease, a condition that keeps the cells in her body from developing the energy they need. Her parents, Vicky and Keith, know Jessica's life will be difficult and short.
"She struggles with swallowing, she struggles with her muscle tone as well," Vicki said. "So as you can see, she is very floppy, she can't really hold her own head up."
"It's a severely life-limiting disorder," Keith admits. "Maybe toddler years or something like that, we don't know."
Yet, while there may be no known cure for Jessica, there is now a potential cure for the condition that caused her illness.
In mothers whose eggs have a healthy nucleus, surrounded by defective mitochondria -- the little batteries that power cells -- that nucleus is transferred to a donor egg, with healthy mitochondria and which has had its nucleus removed.
The hybrid egg, now with the mother's and the egg-donor's DNA in it, is fertilized with the father's sperm. And the resulting embryo then has genetic coding from three parents -- the mother, the egg-donor and the father.
Britain is the first country to sanction the technique, approving it in a House of Commons vote, but only after a heated debate with loaded language about "playing God" and "designer babies."
"Once the genie is out of the bottle, once these procedures that we are being asked to authorize today go ahead, there will be no going back for society," argued MP Fiona Bruce.
"And if this was genetically modified crops, we'd all be up in arms," MP Robert Flello said. "That's what's happening here."
"For the many families affected, this is a light at the end of a very dark tunnel," countered MP Jane Ellison.
The churches in Britain -- both Protestant and Catholic -- oppose the procedure on religious and ethical grounds. But science won the argument.
The first babies could be born using the technique in the next two or three years, if the House of Lords also approves it.