While people covered in moles are aware they face an increased risk of developing skin cancer, new research suggests they may still live longer than those with fewer blemishes.
A study of twins has revealed links between high numbers of moles and a biological marker for slow ageing.
Study leader Dr Veronique Bataille from the Twin Research Unit at King's College London said: "The results of this study are very exciting as they show, for the first time, that moley people who have a slightly increased risk of melanoma may, on the other hand, have the benefit of a reduced rate of ageing.
"This could imply susceptibility to fewer age-related diseases such as heart disease or osteoporosis, for example."
Because moles disappear with age, Dr Bataille's team looked at their relationship with telomere length, a biological indicator of an individual's rate of ageing.
Telomeres are protective bundles of DNA found at the end of chromosomes in all cells.
The research found people with more than 100 moles had longer telomeres, equivalent to living six to seven years longer.
Professor Tim Spector, head of the Twin Research Unit and co-author of the study published in the journal Cancer Epidemiology Biomarkers & Prevention, said: "We now plan to look in more detail at the genes which influence the numbers of moles and to see whether they may also slow down the ageing process in general."