LONDON -- A pair of British twin boys has been born with different skin color, a rare genetic occurrence according to experts.

Video: Click To See Footage Of Twins

In an interview with Britain's Sky News program, mother Kerry Richardson said that the boys were both born white but as they've gotten older one of the boys got darker and the other lighter.

"Over the last few months Layton has got lighter and blonder, like his dad, and Kaydon has gone darker like me," Richardson told The Daily Mail.

These days, she said, the twins attract attention wherever they go.

"Everywhere we go you can see people looking and you can tell they are dying to comment," Kerry said. "I have to explain they really are twins and do have the same parents."

"Sometimes I think that it is going to be really weird for them growing up. But I just look at them as being even more special," she said.

Richardson is of mixed race, with Nigerian and English heritage, while the father is white.

The twins were born July 23, four weeks prematurely.

A genetics expert at Oxford University said such births are rare, as the genes that cause skin color normally mix together. In this case, he said, it appears the genes for skin color didn't combine for some reason and the boys may have inherited different genetic codes from their mother.

"It's probably a million to one chance," international clinical geneticist Dr. Stephen Withers said.

"It was just gradual that we started noticing the difference in their skin color," Richardson said, according to The Daily Mail. "But to me it doesn't matter what they look like. They are my little angels and I would love them whatever color skin they had."