Raised right

Kevin Lewis

March 10, 2015

Why Do Entrepreneurial Parents Have Entrepreneurial Children?

Matthew Lindquist, Joeri Sol & Mirjam Van Praag
Journal of Labor Economics, April 2015, Pages 269-296

We explore the origins of the intergenerational association in entrepreneurship using Swedish adoption data that allow us to quantify the relative importance of prebirth and postbirth factors. We find that parental entrepreneurship increases the probability of children’s entrepreneurship by about 60%. For adoptees, both biological and adoptive parents make significant contributions to this association. These contributions, however, are quite different in size. Postbirth factors account for twice as much as prebirth factors in our decomposition of the intergenerational association in entrepreneurship. We investigate several candidate explanations for this large postbirth factor and present suggestive evidence in favor of role modeling.


A within-family analysis of birth order and intelligence using population conscription data on Swedish men

Kieron Barclay
Intelligence, March–April 2015, Pages 134–143

This study examines the relationship between birth order and intelligence in Sweden. This research question has been of interest for decades, but only one study using a sibling comparison design has found that birth order has a negative effect on intelligence. The data used in this study is Swedish administrative register data, with data on cognitive ability drawn from the military conscription register for men born 1965 to 1977. Within-family comparison linear regression models are used to estimate the difference in cognitive ability by birth order amongst brothers. I find that there is a negative relationship between birth order and cognitive ability. This is consistent in sibling-group-size-specific analyses of sibling groups with two through to six children. Further analyses demonstrate that this negative relationship between birth order and intelligence is consistent in different socioeconomic status groups, and amongst individuals born in the 1960s and 1970s. Analyses of brothers in two-child sibling groups show that the relationship between birth order and intelligence varies by the birth interval. Second borns have a statistically significantly lower cognitive ability score if the birth interval is up to six years, but not if it is longer.


Detrimental for Some? Heterogeneous Effects of Maternal Incarceration on Child Wellbeing

Kristin Turney & Christopher Wildeman
Criminology & Public Policy, February 2015, Pages 125–156

We use data from the Fragile Families and Child Wellbeing Study (N = 3,197) to consider the heterogeneous effects of maternal incarceration on 9-year-old children. We find that maternal incarceration has no average effects on child wellbeing (measured by caregiver-reported internalizing problem behaviors, caregiver-reported externalizing problem behaviors, Peabody Picture Vocabulary Test-Third Edition scores, and child-reported early juvenile delinquency) but that the effects vary by mothers’ propensities for experiencing incarceration. Maternal incarceration is deleterious for children of mothers least likely to experience incarceration but mostly inconsequential for children of mothers more likely to experience incarceration.


Serotonin transporter linked polymorphic region (5-HTTLPR) genotype moderates the longitudinal impact of early caregiving on externalizing behavior

Zoë Brett et al.
Development and Psychopathology, February 2015, Pages 7-18

We examined caregiver report of externalizing behavior from 12 to 54 months of age in 102 children randomized to care as usual in institutions or to newly created high-quality foster care. At baseline no differences by group or genotype in externalizing were found. However, changes in externalizing from baseline to 42 months of age were moderated by the serotonin transporter linked polymorphic region genotype and intervention group, where the slope for short–short (S/S) individuals differed as a function of intervention group. The slope for individuals carrying the long allele did not significantly differ between groups. At 54 months of age, S/S children in the foster care group had the lowest levels of externalizing behavior, while children with the S/S genotype in the care as usual group demonstrated the highest rates of externalizing behavior. No intervention group differences were found in externalizing behavior among children who carried the long allele. These findings, within a randomized controlled trial of foster care compared to continued care as usual, indicate that the serotonin transporter linked polymorphic region genotype moderates the relation between early caregiving environments to predict externalizing behavior in children exposed to early institutional care in a manner most consistent with differential susceptibility.


Maternity leave and children’s cognitive and behavioral development

Michael Baker & Kevin Milligan
Journal of Population Economics, April 2015, Pages 373-391

We investigate the impact of maternity leave on the cognitive and behavioral development of children at ages 4 and 5, following up previous research on these children at younger ages. The impact is identified by legislated increases in the duration of maternity leave in Canada, which significantly increased the amount of first-year maternal care. Our results indicate no positive effect on indices of children’s cognitive and behavioral development. We uncover a small negative impact on PPVT scores.


Nonresident fatherhood and adolescent sexual behavior: A comparison of siblings approach

Rebecca Ryan
Developmental Psychology, February 2015, Pages 211-223

Although voluminous research has linked nonresident fatherhood to riskier sexual behavior in adolescence, including earlier sexual debut, neither the causality of that link nor the mechanism accounting for it has been well-established. Using data from the National Longitudinal Survey of Youth, 1979 — the Young Adult Survey (CNLSY-YA), the present study addresses both questions by comparing the sexual development of siblings discordant for age at father departure from the home and examining results across behavioral (age at first intercourse), biological (pubertal timing), and cognitive (attitudes about childbearing and marriage) sexual outcomes (N = 5,542). Findings indicate that nonresident fatherhood, beginning either at birth or during middle childhood, leads to an earlier sexual debut for girls, but not for boys, an effect likely explained by weak parental monitoring rather than an accelerated reproductive strategy.


Breastfeeding duration and non-verbal IQ in children

Ayesha Sajjad et al.
Journal of Epidemiology & Community Health, forthcoming

Background: Breastfeeding has been related to better cognitive development in children. However, due to methodological challenges, such as confounding, recall bias or insufficient power, the mechanism and nature of the relation remains subject to debate.

Methods: We included 3761 participants of a population-based cohort study from fetal life onwards and examined the association of breastfeeding duration with non-verbal intelligence in children of age 6 years. Maternal and paternal lifestyle, sociodemographic factors, child factors and maternal IQ were tested for their confounding effects on the association.

Results: We observed an initial association between breastfeeding duration and child IQ conferring an advantage of 0.32 (0.20 to 0.44) points for each additional month of breastfeeding. This association strongly attenuated to 0.09 (−0.03 to 0.21) points after adjustment for child factors, sociodemographic factors, parental lifestyle factors and maternal IQ. Similarly, the associations with breastfeeding duration as a categorical variable largely disappeared after confounding factors were added to the models.

Conclusions: The association between breastfeeding and child IQ can be largely explained by sociodemographic factors, parental lifestyle and maternal IQ. Our results cannot confirm beneficial effects of breastfeeding on child intelligence.


Does the Amount of Time Mothers Spend With Children or Adolescents Matter?

Melissa Milkie, Kei Nomaguchi & Kathleen Denny
Journal of Marriage and Family, April 2015, Pages 355–372

Although intensive mothering ideology underscores the irreplaceable nature of mothers' time for children's optimal development, empirical testing of this assumption is scant. Using time diary and survey data from the Panel Study of Income Dynamics Child Development Supplement, the authors examined how the amount of time mothers spent with children ages 3–11 (N = 1,605) and adolescents 12–18 (N = 778) related to offspring behavioral, emotional, and academic outcomes and adolescent risky behavior. Both time mothers spent engaged with and accessible to offspring were assessed. In childhood and adolescence, the amount of maternal time did not matter for offspring behaviors, emotions, or academics, whereas social status factors were important. For adolescents, more engaged maternal time was related to fewer delinquent behaviors, and engaged time with parents together was related to better outcomes. Overall, the amount of mothers' time mattered in nuanced ways, and, unexpectedly, only in adolescence.


Parenting Influence on the Development of Life History Strategy

Curtis Dunkel et al.
Evolution and Human Behavior, forthcoming

Using a newly developed measure of life history strategy, the influence of maternal and paternal sensitivity in childhood and maternal and paternal authoritative parenting in late adolescence on developing life history strategy was examined. Maternal sensitivity and maternal and paternal authoritative parenting were positively correlated with a slow LH strategy. Maternal sensitivity and maternal authoritative parenting each explained unique variance in life history strategy as measured in late adolescence. The results remained after controlling for ethnicity, sex, childhood SES, intelligence, and childhood temperament. Consistent with previous research and theory the results suggest that maternal sensitivity in early childhood affects the development of life history strategy. However, the results also suggest that significant post pubertal plasticity in life history strategy development remains and that parental behavior continues to be influential in an individual’s developing life history strategy.


Unattractive infant faces elicit negative affect from adults

Stevie Schein & Judith Langlois
Infant Behavior and Development, February 2015, Pages 130–134

We examined the relationship between infant attractiveness and adult affect by investigating whether differing levels of infant facial attractiveness elicit facial muscle movement correlated with positive and negative affect from adults (N = 87) using electromyography. Unattractive infant faces evoked significantly more corrugator supercilii and levator labii superioris movement (physiological correlates of negative affect) than attractive infant faces. These results suggest that unattractive infants may be at risk for negative affective responses from adults, though the relationship between those responses and caregiving behavior remains elusive.


Menstrual cycle phase affects discrimination of infant cuteness

Janek Lobmaier et al.
Hormones and Behavior, April 2015, Pages 1–6

Recent studies have shown that women are more sensitive than men to subtle cuteness differences in infant faces. It has been suggested that raised levels in estradiol and progesterone may be responsible for this advantage. We compared young women's sensitivity to computer-manipulated baby faces varying in cuteness. Thirty-six women were tested once during ovulation and once during the luteal phase of their menstrual cycle. In a two alternative forced-choice experiment, participants chose the baby which they thought was cuter (Task 1), younger (Task 2), or the baby that they would prefer to babysit (Task 3). Saliva samples to assess levels of estradiol, progesterone and testosterone were collected at each test session. During ovulation, women were more likely to choose the cuter baby than during the luteal phase, in all three tasks. These results suggest that cuteness discrimination may be driven by cyclic hormonal shifts. However none of the measured hormones were related to increased cuteness sensitivity. We speculate that other hormones than the ones measured here might be responsible for the increased sensitivity to subtle cuteness differences during ovulation.


Effect of Early Institutionalization and Foster Care on Long-term White Matter Development: A Randomized Clinical Trial

Johanna Bick et al.
JAMA Pediatrics, March 2015, Pages 211-219

Objective: To examine associations among neglect in early life, early intervention, and the microstructural integrity of white matter pathways in middle childhood.

Design, Setting, and Participants: The Bucharest Early Intervention Project is a randomized clinical trial of high-quality foster care as an intervention for institutionally reared children in Bucharest, Romania, from 2000 through the present. During infancy, children were randomly selected to remain in an institution or to be placed in foster care. Those who remained in institutions experienced neglect, including social, emotional, linguistic, and cognitive impoverishment. Developmental trajectories of these children were compared with a group of sociodemographically matched children reared in biological families at baseline and several points throughout development. At approximately 8 years of age, 69 of the original 136 children underwent structural magnetic resonance imaging scans.

Main Outcomes and Measures: Four estimates of white matter integrity (fractional anisotropy [FA] and mean [MD], radial [RD], and axial [AD] diffusivity) for 48 white matter tracts throughout the brain were obtained through diffusion tensor imaging.

Results: Significant associations emerged between neglect in early life and microstructural integrity of the body of the corpus callosum (FA, β = 0.01 [P = .01]; RD, β = −0.02 [P = .005]; MD, β = −0.01 [P = .02]) and tracts involved in limbic circuitry (fornix crus [AD, β = 0.02 (P = .046)] and cingulum [RD, β = −0.01 (P = .02); MD, β = −0.01 (P = .049)]), frontostriatal circuitry (anterior [AD, β = −0.01 (P = .02)] and superior [AD, β = −0.02 (P = .02); MD, β = −0.01 (P = .03)] corona radiata and external capsule [right FA, β = 0.01 (P = .03); left FA, β = 0.01 (P = .03); RD, β = −0.01 (P = .01); MD, β = −0.01 (P = .03)]), and sensory processing (medial lemniscus [AD, β = −0.02 (P = .045); MD, β = −0.01 (P = .04)] and retrolenticular internal capsule [FA, β = −0.01 (P = .002); RD, β = 0.01 (P = .003); MD, β = 0.01 (P = .04)]). Follow-up analyses revealed that early intervention promoted more normative white matter development among previously neglected children who entered foster care.

Conclusions and Relevance: Results suggest that removal from conditions of neglect in early life and entry into a high-quality family environment can support more normative trajectories of white matter growth. Our findings have implications for public health and policy efforts designed to promote normative brain development among vulnerable children.


Young adults’ reactions to infant crying

Christine Hechler, Roseriet Beijers & Carolina de Weerth
Infant Behavior and Development, February 2015, Pages 41–48

Aim: To determine whether young childless adults show negative emotions and cognitive disturbances when listening to infant crying, compared to other disturbing noises, and whether negative emotions and cognitive disturbances are associated.

Methods: We tested the cognitive performances and emotional reactions of 120 childless participants on a working memory task while being subjected to different disturbing noises including infant crying.

Results: Participants had the least correct trials on the working memory task, and showed the most negative emotions, when hearing infant crying as compared to the other noises. Participants also showed less positive emotions when hearing infant crying as compared to working in silence. Overall, negative emotions were associated with less correct trials on the working memory task, except in the infant crying condition. Furthermore, cognitive performance and emotional reactions to infant crying were unrelated to personality characteristics.

Conclusion: Negative emotions and cognitive disturbances may be general adult responses to infant crying that are not limited to parents. These results suggest a broadly present human emotional and cognitive response to infant crying, that may underlie a general predisposition to care for infants in distress.


Can’t buy mommy’s love? Universal childcare and children’s long-term cognitive development

Christina Felfe, Natalia Nollenberger & Núria Rodríguez-Planas
Journal of Population Economics, April 2015, Pages 393-422

What happens to children’s long-run cognitive development when introducing universal high-quality childcare for 3-year-olds mainly crowds out family care? To answer this question, we take advantage of a sizeable expansion of publicly subsidized full-time high-quality childcare for 3-year-olds in Spain in the early 1990s. Identification relies on variation in the initial speed of the expansion of childcare slots across states. Using a difference-in-difference approach, we find strong evidence for sizeable improvements in children’s reading skills at age 15 (0.15 standard deviation) and weak evidence for a reduction in grade retentions during primary school (2.5 percentage points). The effects are driven by girls and disadvantaged children.


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