This is consistent with the sibling tutoring hypothesis, inasmuch as last-born children are similar to only children in lacking a younger sibling to tutor.
That is, ' unicis' stands for y: ' the only children of their respective parents'.
These findings suggest that only children are not disadvantaged.
Even among adolescents, only children had higher scores on tests of general ability than middle-born children.
In this study, only children <15 years of age have been sampled.
Table 3 presents the results comparing only children with all others by five types of intellectual ability: general, verbal, quantitative, spatial and non-verbal.
Only children with a minimum of ten attempts in a pronoun paradigm were included in these correlations.
However, only children who met the above explicit criteria were retained.
