all twins participating in TOSS and all family members who participated as part of cohort 2. Since the first TOSS cohort only includes twin mothers, DNA is available for a larger amount of adult women than men. DNA was extracted from saliva samples that were collected using OraGeneR DNA self-collection kit. Zygosity was determined primarily by genotyping. A total of 2309 individuals (1463 women and 947 men) provided usable DNA samples.
