Using information on 1045 pairs of Japanese monozygotic twins, we examined differences in education by considering both the years of schooling (quantity) and the reputation of the last attended school (quality). We found that a difference in learning performance at 15 years of age is one of the key factors determining the differences. We also found that a female eldest child in the family from the 1950s and 1960s birth cohorts averaged 0.54 years less schooling than did her ‘younger’ twin. However, for the same birth cohorts, a male eldest child in the family generally had access to higher‐quality education than his ‘younger’ twin. Nonetheless, as the Japanese economy matured in the 1970s and thereafter, educational differences between twins disappeared, regardless of gender and sibling order.