A Bio-Behavioral Model to Explain Gender-Conditional Parity Progression Patterns: Applications to Danish Twin Registry Data

Joseph L. Rodgers, University of Oklahoma
Hans-Peter Kohler, University of Pennsylvania
Kaare Christensen, University of Southern Denmark

This presentation defines and presents a model of gender-conditional parity progression that explicitly separates the biology of gender from behavioral decision making. Parity progression ratios assume that the probability of a female or couple's next child, conditional on the current number of children, is indicative of behavioral responses to parity patterns. This model was proposed by Rodgers and Doughty (2001), and fit to U.S. data from the NLSY79. The behavioral parameters in the model were used to estimate behavioral stopping parameters, and the biological parameters were used to asses whether gender patterns have a genetic basis. We apply the model to Danish twin data, which helps us asses the cross-cultural status of the earlier findings, and adds to the model estimates the effect of multiple births on gender- and parity-conditional fertility patterns. Invariance of results across demographic subgroups is evaluated.