Committees. The characteristics of this population-based sample and its generalizability have been previously reported.22 Briefly, children in Avon had parents with a similar racial distribution as the general UK population (5.1% versus 6.4% nonwhite, in Avon and the entire United Kingdom, respectively), level of education (14.0 % vs 13.7% with university degrees), and the rate of single parent households at age 5 (4% versus 5%), although children in Avon were significantly less likely to have a father working in manual labor (51.6% versus 65.1%).
