Previous evidence suggests that the lactase gene C/T− 13910 polymorphism (rs4988235) is associated with avoidance of milk products and lower Ca intake. We examined whether the consumption of milk and milk products and the intakes of milk nutrients differ between the lactase genotypes from childhood to young adulthood. Subjects belong to the Cardiovascular Risk in Young Finns Study where the first cross-sectional surveys were conducted in 1980 (n 3596), with follow-up studies in 1983, 1986, 1989, 1992 and 2001 (n 2620). The same dietary questionnaire was used throughout the follow-up to collect data on habitual consumption of milk and milk products in all subjects, and daily nutrient intakes were assessed with 48 h dietary recalls in 50 % of the subjects. Subjects with the lactase non-persistence (C/C− 13910) genotype consumed less milk since childhood, but the consumption of other milk products did not differ between the genotypes. In adult females, the lactose content of milk products consumed was lower (P = 0·003), and in both sexes low-lactose and milk-free diets were more common in the C/C− 13910 genotype than in the other genotypes. Inadequate Ca intake was most common in females with the C/C− 13910 genotype as early as in childhood (15–63 %), but in males only in adulthood (24 %). In adult females, preference for low-lactose milk and milk products equalised the differences in Ca intake between the genotypes. Thus, in those with the C/C− 13910 genotype, preference for low-lactose milk and milk products may decrease the risk for inadequate Ca intake.