Table 1.

Detailed family structure of the QTIM and HCP samples

Total sample size (individuals) for phenotypic analysis834890
Final sample size (individuals) for twin modeling833*853**‡
Incl.N complete trios23184
Incl.N MZ pairs + one sibling975
N DZ pairs + one sibling1471
N sibling trios038
N complete pairs275109
Incl.N MZ pairs10114
N DZ pairs14219
N twin-sib pairs3238
N sibling pairs038
N singletons21483
Incl.N twins18133
N non-twin siblings3350
  • * One individual from a family of four siblings was excluded for twin modeling, i.e., maximum family size restricted to three individuals (twin and/or non-twin siblings).

  • ** Thirty-seven individuals from families with more than four siblings were excluded with no effect on the sample characteristics (mean age 28, SD = 3.7, range 22–37, 56.5% females after exclusion).

  • To maximize the HCP sample, 12 half-siblings were included (categorized as siblings in twin analysis); this low number should not affect estimates from twin modeling.