Table 3.

Full model estimates of the proportion of variation in two gambling phenotypes attributable to additive genetic, shared environmental, and unique environmental factors.

	Proportion of Variation
Gambling Phenotype	Additive Genetic	Shared Environment	Unique Environment
	Full Sample
Any gambling	.00 (ne)	.50 (.04, .95)	.50 (.31, .70)
Gambling Activity Count	.00 (ne)	.38 (.30, .46)	.62 (.54, .70)
	Men
Any Gambling	.00 (ne)	.42 (.20, .65)	.58 (.35, .80)
Gambling Activity Count	.00 (ne)	.38 (.26, .50)	.62 (.50, .74)
	Women
Any Gambling	.00 (ne)	.55 (.37, .73)	.45 (.27, .64)
Gambling Activity Count	.00 (ne)	.38 (.26, .49)	.62 (.51, .74)

Note: Analyses performed using data from like-sex twins only. 95% confidence intervals are in parentheses, `ne' = not estimable (because the monozygotic were smaller than the dizygotic twin correlations).