Twin sisters Alicia and Jasmin Singerl certainly make people look twice.  Alicia has dark brown eyes and complexion, and Jasmin is blue-eyed and fair-skinned. Experts say the chance of twins being born with such different physical characteristics is about one in seventeen million. (w/pic)

The sisters from Burpengary, north of Brisbane, were born in May.

Mother Natasha Knight, 35, has Jamaican-English heritage, and their father, Michael Singerl, 34, was born in Germany.

The couple, who are engaged, also have a five-year-old daughter, Taylah, who is blue-eyed with blonde hair and a light olive complexion.

Ms Knight said she was shocked when she saw the difference between her daughters.

"It’s just amazing . . . they are so different,” she said. "You could see there was a colour difference straight away. We couldn’t believe it.

"Alicia’s eyes were brown and her hair was dark. Jasmin’s eyes were blue and her hair was white – you could hardly see her hair or her eyebrows.

"We were joking when I was pregnant about what if one baby looked like me and one looked like Michael. We joked about one light one, one dark one, so it was amazing when it actually happened.

"When we go out, people stop and ask if they are twins. Other people will look but not say anything. Maybe they think I am babysitting one of them.

Twins / Jamie Hanson

Yes, they’re twins … sisters Alicia and Jasmin make people look twice.

"Someone even asked me if I was sure there wasn’t a mix-up at the hospital. But there was no mix-up – they are my girls and they are both so beautiful.

"It will be interesting when they go to school and they will probably wonder why they look so different from each other. I guess the easiest way to explain it will be to say one took after mum, one took after dad.”

Genetics experts say that in most cases a mixed-race woman’s eggs will be a mixture of genes for both black and white skin.

However, much more rarely, the eggs may contain genes for predominantly one skin colour.

In this case, Ms Knight has released two such eggs – one with predominantly dark pigmentation genes and one with predominantly fair genes. Non-identical twins are conceived when two eggs are fertilised by two sperm at the same time, which has odds in itself of about 100-1.

Clinical geneticist Stephen Withers said the likelihood of a mixed-race woman having eggs that were predominantly for one skin colour was rare enough, let alone releasing two of them simultaneously and producing twins.

"It’s probably a million to one,” Dr Withers said. "It’s a terrifically rare phenomenon.”