Background data on the participants.

Note. One of the bilinguals in the younger sample, who was reported to speak three languages fluently, was excluded; Mother educational level = highest educational level attained by the mother of the child; Father educational level = highest educational level attained by the father of the child; Level 1 = Comprehensive school; Level 2 = Upper secondary education or vocational education; Level 3 = Lower-degree level tertiary education; Level 4 = Higher-degree level tertiary education or doctorate.aInformation on this point was not obtained from some participants.Background data on the participants.