RT Article T1 IQ similarities in twin, siblings, half-siblings, cousins, and random pairs JF Intelligence VO 11 IS 3 SP 199 OP 206 A1 Rodgers, Joseph L. A2 Rowe, David C. LA English YR 1987 UL https://krimdok.uni-tuebingen.de/Record/1637991193 K1 Intelligenzforschung K1 Zwillingsforschung