A Labour MP has apologised after saying inbreeding may be partly to blame for a rise in cases of diabetes in his Norfolk constituency.
Dr Gibson said inbreeding in Norfolk began "way back in the past"
Family relationships could have led to a sharing of a gene linked to the condition, suggested former science lecturer Ian Gibson.
A consultant at a local hospital said the remarks were "disgraceful".
That prompted an apology from Dr Gibson, who said he had never meant to cause any offence.
Research suggests about 345 children in Norfolk suffer from type-1 diabetes, more than twice the 160 predicted cases for the county.
In an interview with BBC Radio Norfolk on Thursday, Norwich North MP Dr Gibson said there could be genetic reasons for the illness.
"In a county where it's from way back in the past there have been smaller numbers of people, localised in small areas there may be some degree of familiarity, family relationships you know in terms of brothers and other families with the same name and so on," he said.
He said that some people thought of Norwich as "closed off" which was "nonsense".
"It does happen everywhere, there are different groups of people who for historical reasons have certain genetics which other people don't.
"As I said there are different frequencies of blood groups in different parts of the UK. Who knows why, but it could be an explanation of certain illnesses."
The comments angered Dr Ketan Dhatariya, a diabetologist at the Norfolk and Norwich University Hospital.
He told the Eastern Daily Press newspaper: "It's an insult to people with type-1 diabetes and their families and it's an insult to people in Norfolk.
"There's no suggestion that that is the case. It's not the way that genetics works.
"There is a genetic element, but it may be triggered by an environmental factor. Nobody knows why it is rising."
On Friday, Dr Gibson told BBC Radio 4's Today programme he wished he had never made his original comments.
"It's obviously caused a lot of offence and for that I unreservedly apologise," he said.
A study into diabetes is about to begin and Mr Gibson said he hoped it would look at the influence of genetics.
Words like inbreeding and outbreeding were professional genetic terms he said but for the public they had different connotations, he said.