Post-reproductive life span of spouses correlates better than of full and half siblings in a genetically homogeneous high status group

Ulrich O. Mueller, Federal Institute for Population Research (BiB)

Many genes moderately affecting the life span have been identified, social and lifestyle factors may have greater importance, especially for the post-reproductive life span. Determining the relative contributions of genes vs. environment in this matter depends on the genetic vs. the environmental homogeneity of the study population. We study the associations of lifespan among full and half siblings and among spouses in a genetically homogeneous top status group with many potential confounders controlled: the 1,672 legitimate births in the Royal Houses of Europe to King George I of Great Britain, (1660–1727), and his wife Sophie Dorothea of Celle (1666–1726) and their direct descendants, between 1 January 1683 and 31 December 1939. Deaths until 31st December 2014 were recorded. To this group including children belong all present reigning monarchs in Europe. Only ever married subjects surviving to at last 45 years of age but dead by 2014 were analysed. 255 pairs of full brothers and 209 pairs of full sisters. A person’s life span was predicted by first spouse’s life span, with r=.251, p=.026 for women and r=.227, p=.032 for men. On the other hand, no correlation was found in the life span of full brothers with r=.118 (p=.270) or full sisters (r=–.033, p=.763), nor in the life span of half brothers or half sisters. We conclude that in this genetically homogeneous population, in which genetic distance between spouses was lower than between siblings, but may have varied little, with a similar high standard of living and the best medical care of the time, life style factors - like nutrition, exercise, personal hygiene, sanitation, addictions – that are more share between spouses than between siblings in adult life, may have mattered more than genes for individual longevity.