Lady Deech, who used to chair the Human Fertilisation and Embryology Authority, has said that first cousins who marry should be made aware of the genetic risks transmitted to off-spring.
Speaking to Radio 4's The World At One, that the issue should not be a "no-go area". She added that first cousins must be provided all information.
In an interview to BBC's Martha Kearney, Ladt Deech said such marriages must not be banned. However the risks must also not remain hidden.