Using a new twins sample, presents new estimates of schooling returns and "ability" bias and tests that bias's significance. Ability bias may exist even if ability's genetically-endowed component does not affect schooling decisions directly when correlated with other family characteristics (like income) that do affect schooling. (19…

If maternal expressed emotion is an environmental risk factor for children's antisocial behavior problems, it should account for behavioral differences between siblings growing up in the same family even after genetic influences on children's behavior problems are taken into account. This hypothesis was tested in the Environmental Risk…

Reexamines Ashenfelter and Krueger's estimates of schooling returns (13%), using three additional years of the same twins survey. Finds a 10% return per year of schooling completed. The within-twin regression estimate of schooling's effect in the log wage is smaller than the cross-sectional estimate. (14 references) (MLH)

Data from a large sample of Australian twins indicate that 50 to 65 percent of variance in educational attainments can be attributed to genetic endowments. Only about 25 to 40 percent may be due to environmental factors, depending on adjustments for measurement error and assortative mating. (Contains 51 references.) (MLH)

Lower birth weight babies have worse outcomes, both short-run in terms of one year mortality rates and longer run in terms of educational attainment and earnings. However, recent research has called into question whether birth weight itself is important or whether it simply reflects other hard-to-measure characteristics. By applying within twin…

Recent within-twin estimates of schooling returns are considerably higher than existing estimates. This paper shows that small ability differences among twins can yield more upward omitted-ability bias (and more upward bias overall) in the instrumental variables estimate correcting for measurement error than in the standard within-twin estimate.…

There is an extensive theoretical literature that postulates a trade off between child quantity and quality within a family. However, there is little causal evidence that speaks to this theory. Using a rich dataset on the entire population of Norway over an extended period of time, we examine the effects of family size and birth order on the…