Comparing Survival Outcomes for the Siblings of Twins

Shannen L. Robson, University of Utah

We have shown that twinning is a marker of a robust maternal phenotype. Here we examine mortality patterns of the singleton offspring of mothers of twins compared to the offspring of non-twinning mothers to determine whether the siblings of twins possess the enhanced phenotype of their mothers. From the Utah Population Database (UPDB) we compared the survival of 463,438 offspring of singleton-only bearing mothers and singleton siblings of twin-bearing mothers. Using survival analyses we found that males had higher mortality at all ages but experience a protective effect if a sibling of a twin. Singleton offspring immediately following a twinset did not suffer significant survival disadvantages. However, subsequent male siblings who survive to age 18 experience an improvement in survival. No survival benefits were detected for singleton sisters of twins. Further work will explore the fitness implications of being born to a twinning mother.

  See extended abstract

Presented in Poster Session 2