H. Hill Goldsmith1 & Kathryn S. Lemery1
We report the establishment of a statewide infancy and early childhood twin panel for behavioral and health-related research. The base population comprised approximately 700 twin pairs per year since 1989. The ethnic breakdown of twin mothers was 87% White, 12% Black, and 1% American Indian, Asian and other. We interviewed the twins' primary caregiver over the telephone for a subset of over 500 families with 3 to 7 year old twins. Additionally, we sent a packet of questionnaires for both mothers and fathers to complete. We asked parents about their twins' temperaments, the sibling relationship, their own parenting style and personality, and levels of family emotional expressiveness. Considering the relationship between difficult temperament in the twins and sibling conflict (average phenotypic r = .40), we found that similarity between the twins was explained largely by shared genes for difficult temperament (MZ ICR = .76; DZ ICR = .25), and shared environment for sibling conflict (MZ ICR = .68; DZ ICR = .57). We fit a direction of causation model to this data. From detailed temperament questionnaires, we identified subgroups of twins with extreme temperaments for further study. We fit DF extreme group regressions to this data. We are currently planning a laboratory followup with structured psychopathology assessment of extreme temperamental groups.
Address: Psychology Department, 1202 West Johnson Street, University of Wisconsin-Madison, Madison, WI 53706., (608) 262-1040 phone, (608) 265-3649 fax, hhgoldsm@facstaff.wisc.edu
1Department of Psychology, University of Wisconsin-Madison, 1202 West Johnson Street, Madison, Wisconsin 53706 2Supported by NIMH Grant MH50560