Those who participated in the Aberdeen Children of the 1950s project, which saw all primary pupils aged seven to 12 surveyed by the Medical Research Council in 1962, have been contacted.
They have been asked to take part in the Scottish Family Health Study, which is recruiting 50,000 people.
It aims to investigate why diseases such as cancer can run in families.
Those recruited will have their health tracked, with the intention of creating a Scottish "bio-bank" containing genetic, medical and family history and lifestyle information.
This will allow researchers to investigate the contribution of genetic and environmental factors to common conditions.
Blair Smith, a GP and professor of primary care medicine at Aberdeen University, will run the project.
He said: "We know that many diseases such as cancer, heart disease, mental illness and diabetes run in families and that tells us that genes are important.
"But we don't know yet which genes are important or how they relate to other things such as lifestyle.
"We can get more information about genes by studying DNA which carries the genetic blueprint handed down through the generations.
"That is why we are collecting and analysing blood samples and health information from thousands of families across Scotland."
He said the data gathered would help future research into the prevention, treatment and diagnosis of illnesses.
Aberdonians who were involved in health research nearly 50 years ago have been asked to sign up to another study.