Guang Guo

The Mechanisms Mediating the Effects of Poverty on Children's Intellectual Development *

Although adverse consequences of poverty for children are documented widely, little is understood about the mechanisms through which the effects of poverty disadvantage young children. In this analysis we investigate multiple mechanisms through which poverty affects a child’s intellectual development. Using data from the NLSY and structural equation models, we have constructed five latent factors (cognitive stimulation, parenting style, physical environment, child’s ill health at birth, and ill health in childhood) and have allowed these factors, along with child care, to mediate the effects of poverty and other exogenous variables. We produce two main findings. First, the influence of family poverty on children’s intellectual development is mediated completely by the intervening mechanisms measured by our latent factors. Second, our analysis points to cognitive stimulation in the home, and (to a lesser extent) to parenting style, physical environment of the home, and poor child health at birth, as mediating factors that are affected by lack of income and that influence children’s intellectual development.

Sexy Media Matter: Exposure to Sexual Content in Music, Movies, Television, and Magazines Predicts Black and White Adolescents' Sexual Behavior

OBJECTIVE. To assess over time whether exposure to sexual content in 4 mass media (television, movies, music, and magazines) used by early adolescents predicts sexual behavior in middle adolescence. METHODS. An in-home longitudinal survey of 1017 black and white adolescents from 14 middle schools in central North Carolina was conducted. Each teen was interviewed at baseline when he or she was 12 to 14 years old and again 2 years later using a computer-assisted self interview (audio computer-assisted self-interview) to ensure confidentiality. A new measure of each teen’s sexual media diet (SMD) was constructed by weighting the frequency of use of 4 media by the frequency of sexual content in each television show, movie, music album, and magazine the teen used regularly. RESULTS. White adolescents in the top quintile of sexual media diet when 12 to 14 years old were 2.2 times more likely to have had sexual intercourse when 14 to 16 years old than those who were in the lowest SMD quintile, even after a number of other relevant factors, including baseline sexual behavior, were introduced. The relationship was not statistically significant for black adolescents after controlling for other factors that were more predictive, including parental disapproval of teen sex and perceived permissive peer sexual norms. CONCLUSIONS. Exposure to sexual content in music, movies, television, and magazines accelerates white adolescents’ sexual activity and increases their risk of engaging in early sexual intercourse. Black teens appear more influenced by perceptions of their parents’ expectations and their friends’ sexual behavior than by what they see and hear in the media.

Sibship size and intellectual development: Is the relationship causal?

In this study we test the alternative interpretation of the effect of sibship size on childs intellectual development through sibling analysis and analysis of repeated measures of the same individuals. Both analyses are variations of change models or fixed-effects models. Change models enable us to control permanent family effects including family socioeconomic status (SES) family genetic makeup and intellectual atmosphere in the home by `differencing them out. Thus we can determine if and how much the sibship-size effect is confounded by other family influences that are difficult or impossible to control in conventional regression analysis. The data are from the [U.S.] National Longitudinal Survey of Youth (NLSY). Also included are comments by Meredith Phillips (pp. 188-92) and D. B. Downey B. Powell L. C. Steelman and S. Pribesh (pp. 193-98) and a reply by Guo and VanWey (pp. 199-206). (EXCERPT)

The Integration of Genetic Propensities into Social-Control Models of Delinquency and Violence among Male Youths

This study, drawing on approximately 1,100 males from the National Longitudinal Study of Adolescent Health, demonstrates the importance of genetics, and genetic-environmental interactions, for understanding adolescent delinquency and violence. Our analyses show that three genetic polymorphisms—specifically, the 30-bp promoter-region variable number tandem repeat (VNTR) in MAOA, the 40-bp VNTR in DAT1, and the Taq1 polymorphism in DRD2—are significant predictors of serious and violent delinquency when added to a social-control model of delinquency. Importantly, findings also show that the genetic effects of DRD2 and MAOA are conditional and interact with family processes, school processes, and friendship networks. These results, which are among the first that link molecular genetic variants to delinquency, significantly expand our understanding of delinquent and violent behavior, and they highlight the need to simultaneously consider their social and genetic origins.

Estimating a Multivariate Proportional Hazards Model for Clustered Data Using the EM Algorithm, with an Application to Child Survival in Guatemala

Abstract This article discusses a random-effects model for the analysis of clustered survival times, such as those reflecting the mortality experience of children in the same family. We describe parametric and nonparametric approaches to the specification of the random effect and show how the model may be fitted using an accelerated EM algorithm. We then fit two specifications of the model to child survival data from Guatemala. These data had been analyzed before using standard hazard models that ignore cluster effects.

The Social Influences on the Realization of Genetic Potential for Intellectual Development

Much of sociological analysis is devoted to assessing the relative importance of ascribed and achieved characteristics for social mobility. In this article, we extend this line of sociological work by focusing on childrens differential opportunity to achieve their genetic potential for intellectual development. We hypothesize that the extent to which a child realizes his or her genetic potential depends on socioeconomic environment. Using a large sibling sample collected by the National Longitudinal Study of Adolescent Health, we test this hypothesis with a variant of the Peabody Picture Vocabulary Test (PPVT) as the dependent variable. When measures of social environment are considered simultaneously, parental unemployment and ethnicity have a significant effect on the extent to which genetic potential for intellectual development is realized. Our findings suggest that policymakers can help children in disadvantaged environments realize full genetic potential for intellectual development by altering their social circumstances.

Gender differences in associations between depressive symptoms and patterns of substance use and risky sexual behavior among a nationally representative sample of U.S. adolescents

SummaryObjective: This study uses a cluster analysis of adolescents, based on their substance use and sexual risk behaviors, to 1) examine associations between risk behavior patterns and depressive symptoms, stratified by gender, and 2) examine gender differences in risk for depression. Methods: Data are from a nationally representative survey of over 20,000 U.S. adolescents. Logistic regression was used to examine the associations between 16 risk behavior patterns and current depressive symptoms by gender. Results: Compared to abstention, involvement in common adolescent risk behaviors (drinking, smoking, and sexual intercourse) was associated with increased odds of depressive symptoms in both sexes. However, sex differences in depressive symptoms vary by risk behavior pattern. There were no differences in odds for depressive symptoms between abstaining male and female adolescents (OR = 1.07, 95% CI 0.70–1.62). There were also few sex differences in odds of depressive symptoms within the highest-risk behavior profiles. Among adolescents showing light and moderate risk behavior patterns, females experienced significantly more depressive symptoms than males. Conclusions: Adolescents who engage in risk behaviors are at increased risk for depressive symptoms. Girls engaging in low and moderate substance use and sexual activity experience more depressive symptoms than boys with similar behavior. Screening for depression is indicated for female adolescents engaging in even experimental risk behaviors.

The VNTR 2 repeat in MAOA and delinquent behavior in adolescence and young adulthood: associations and MAOA promoter activity

Genetic studies of delinquent and criminal behavior are rare in spite of the wide recognition that individuals may differ in their propensity for delinquency and criminality. Using 2524 participants in Add Health in the United States, the present study demonstrates a link between the rare 2 repeat of the 30-bp VNTR in the MAOA gene and much higher levels of self-reported serious and violent delinquency. The evidence is based on a statistical association analysis and a functional analysis of MAOA promoter activity using two human brain-derived cell lines: neuroblastoma SH-SY5Y and human glioblastoma 1242-MG. The association analysis shows that men with a 2R report a level of serious delinquency and violent delinquency in adolescence and young adulthood that were about twice (CI: (0.21, 3.24), P=0.025; and CI: (0.37, 2.5), P=0.008 for serious and violent delinquency, respectively) as high as those for participants with the other variants. The results for women are similar, but weaker. In the functional analysis, the 2 repeat exhibits much lower levels of promoter activity than the 3 or 4 repeat.

The mixed or multilevel model for behavior genetic analysis.

We propose the mixed model or multilevel model as a general alternative approach to existing behavior genetic analysis—an alternative to correlation analysis, the DeFries-Fulker analysis, and structural equation modeling. The mixed or multilevel model handles readily families of behavioral genetic data, which include paired sibling data (e.g., pairs of MZ and DZ twins) and clustered sibling data (e.g., a family of more than two biological siblings) as special cases. Not only can a family of behavioral genetic data have more than two siblings, it can also contain multiple types of siblings (e.g., a pair of MZ twins, a pair of DZ twins, a full sibling, and a half sibling). In contrast to the traditional approaches, the mixed or multilevel model is insensitive to the order of the siblings in a sibling cluster. We apply our approach to a large, nationally representative behavior genetic sample collected recently by the Add Health Study. We demonstrate the approach through several applications using both clustered and family complex behavioral genetic data: conventional variance decomposition analysis, analysis of interactions between genetic and environmental influences, and analysis of the possible genetic basis for friendship selection. We compare results from the mixed or multilevel model, Pearsons correlation analysis, and the structural equation model.

Age at First Sexual Intercourse, Genes, and Social Context: Evidence from Twins and the Dopamine D4 Receptor Gene

We carried out two distinct types of genetic analysis with data from the National Longitudinal Study of Adolescent Health. The first was a non-DNA twin analysis using monozygotic (identical) and same-sex dizygotic (fraternal) twins. The second analysis investigates the association between age at first sexual intercourse and the 48-bp repeat polymorphism in the dopamine receptor D4 gene (DRD4). The twin analysis shows that MZ twins correlate their timing of first sex to a much greater extent than do the same-sex DZ twins. Our analysis of the polymorphisms in DRD4 indicates that those with an any-3R genotype experienced a risk of first sexual intercourse 23% (p=.016), 233% (p=.0001), 28% (p=.012), and 69% (p=.006) higher than those with an other/other (or any-4R) genotype in the all-ethnicities (n=2,552), Asian, white, and Hispanic samples, respectively. The risk of first sex does not differ between the two genotypes in the African American sample. These results were obtained after adjusting the standard socioeconomic covariates, including gender, parental education, family structure, and community poverty in the regression model. Evidence from both twin and genetic-variant analyses points to a role of genes in the timing of first sexual intercourse.