Structural genetic variants like copy number variants (CNVs) comprise a large part of human genetic variation and may be inherited as well as somatically acquired. Recent studies have reported the presence of somatically acquired structural variants in the human genome and it has been suggested that they may accumulate in elderly individuals. To further explore the presence and the age-related acquisition of somatic structural variants in the human genome, we investigated CNVs acquired over a period of 10 years in 86 elderly Danish twins as well as CNV discordances between co-twins of 18 monozygotic twin pairs. Furthermore, the presence of mosaic structural variants was explored. We identified four mosaic acquired uniparental disomy events on chromosome 4q and 14q in the follow-up samples from four individuals, and our study thereby supports the increasing prevalence of somatic mosaic variants with age.