What happens if first cousins have a baby

West Hartford, Connecticut. Adult Outpatient Psychiatrist. Renton, Washington State. Charlotte, North Carolina.

New Jersey. Family Medicine. Senior Focused Primary Care Physician. State College, Pennsylvania. Having a baby with a first cousin more than doubles the risk of congenital problems such as heart and lung defects, cleft palettes and extra fingers, according to the largest study of its kind in the UK. The study is part of the wider Born in Bradford study , one of the biggest UK studies of its kind which charts a group of more than 13, children born in the city between and Although the absolute risk is still considered very small, meaning that in general the majority of babies are unaffected, first cousin marriages greatly increase birth defects and the chance of a baby dying early.

The national rate for congenital defects is around in every 10, babies, but in Bradford this nearly doubles to about per 10, births.

Other hotspots include Birmingham. Babies of Pakistani origin also account for the highest rate of infant death in England and Wales and congenital problems the most common cause in children younger than The researchers also found an expected increased risk of birth defects in babies born to white British women over the age of Remember, we all have two copies of each of our genes -- one from mom and one from dad.

We also have on average around disease genes each. So how come we all aren't wracked by genetic diseases? Because most of these "bad" copies of genes are recessive. What recessive means is that you need both copies to be bad to get a disease -- a single good copy can save you.

If we all shared the same disease genes, then the likelihood of kids getting these diseases would be high. But we don't. Everyone has a different set of hidden disease genes so that the odds are against people each giving one of the same bad genes to their kids. Now, the more closely related two people are, the more likely it is that they'll share the same set of hidden disease genes.

People might have thought that first cousins were too closely related and so there would be a big increase in genetic diseases if cousins marry. The data doesn't really show this. And if we think about it, it probably isn't surprising that the risk is small for first cousins. There are lots of places in the Middle East, Africa and Asia where marriages between first cousins are encouraged.

There is no rampant genetic disease in these places suggesting all along that the risk was low.