Table 1.

Demographics and descriptive statistics by sample

	Netherlands	Finland	Minnesota
N. Individuals	12,987	5,888	2,742
Age range	17–97	22–37	22–49
Age mean (SD)	32.2 (14.8)	31.3 (4.2)	36.2 (6.9)
% Female	67.2%	56.9%	55.2%
% MZ	47.0%	32.2%	62.2%
% OS DZ	25.3%	35.5%	0%
Years of data collection	2009–2013	2006–2012	2013–2022
% Yes RSI	33.2%	47.5%	44.7%
% Yes CI	29.5%	25.7%	62.9%

Note N refers to number; MZ refers to monozygotic; DZ OS refers to opposite-sex pairs dizygotic pairs; RSI refers to regular smoking initiation; CI refers to cannabis initiation