In a novel finding, Robert Plomin and colleagues suggest that negative aspects of parenting are more heritable than positive aspects. They call this The Dark Side of parenting. The effect is interesting and subtle: it suggests that whilst parents are generally consistent in their handling of their children, some genetically driven characteristics of their children lead them into more negative parenting styles.
Genetics of Parenting: The Power of the Dark Side
Bonamy R. Oliver, Maciej Trzaskowski, and Robert Plomin
Online First Publication, Developmental Psychology, December 23, 2013. doi: 10.1037/a0035388
They argue that the “dark” side of genetically driven child characteristics plays a bigger role in eliciting parental negativity than do other child characteristics in
eliciting positivity across feelings and control. For example, parental negativity encompassing hostility and harsh parenting may be more responsive to genetically driven challenging child temperament than positive features such as warmth and calmness are to less challenging traits. In simple terms, even peaceable parents get irritable with difficult children.
Theoretical and empirical perspectives on parenting have remained largely founded in Baumrind’s earlier work on parenting styles, which at its core, focused attention on two key aspects of parenting—responsiveness/warmth and demandingness/
control (Baumrind, 1973). While researchers have distinguished aspects of parenting further, most notably in the area of parental control (e.g., Barber & Harmon, 2002) and have varied in their construct labels, these two broad dimensions have been endorsed through numerous studies that have sought to characterize them
Here, we have conceptualized these parenting dimensions as parental feelings (warmth, closeness, hostility, frustration) and parental control (discipline strategies
such as remaining firm and the use of physical discipline); these dimensions have shown robust modest to moderate associations to children’s outcomes (e.g., Parke & Buriel, 2006).
Reviews of behavioral genetic studies have noted that control aspects of parenting tend to yield low estimates of heritability while parental feelings yield moderate estimates (Kendler & Baker, 2007; Plomin, 1994; Rowe, 1981, 1983). To be clear, in
child-based studies, these findings suggest that genetically influenced child characteristics may be more important for eliciting parental feelings than control. However, research has seldom distinguished between positive and negative parental feelings and particularly between positive and negative control strategies. Blurring
the positive and negative sides of feelings and control may mask important underlying foundations of parenting. Harsh discipline and effective supervision, for example, may not be opposite ends of a single continuum, and neither may hostility and warmth. Thus, we hypothesized that the underlying genetic architecture of these aspects of parenting may also be distinct. Specifically, following existing relevant family research as well as work outside the field we predicted that negativity would show greater heritability than positivity across parental feelings and control as well as within parental feelings and within control.
The sampling frame for the current study was the Twins Early Development Study (TEDS), a population-based, longitudinal study of twins born in England and Wales in 1994–1996, recruited from U.K. birth records. Participants are somewhat better educated than average, but are otherwise representative of the UK.
The current study included 2,260 twin pairs at age 9 (1,202 MZ and 1,058 DZ; 1,034
boys and 1,226 girls), 3,850 twin pairs at age 12 (2,027 MZ and 1,823 DZ; 1,752 boys and 2,098 girls), and 2,293 twin pairs at age 14 (1,231 MZ and 1,062 DZ; 1,028 boys and 1,265 girls).
We generated eight scales from identical parent-report measures at child ages 9, 12, and 14 years of parental feelings and control. For feelings, we used an adapted short form (seven items) of the Parental Feelings Questionnaire (PFQ; Deater-Deckard, 2000) and for control, a short (four-item) discipline (parenting strategies questionnaire adapted from Deater-Deckard, Dodge, Bates, and Pettit (1998). Two
standard composite measures were created at each age from the PFQ and Discipline questionnaires: Feelings from seven PFQ items, including the three positive (e.g., “I feel close to my child”) and four negative items (e.g., “I feel frustrated by my child”) and Control comprising four discipline items including two positive (e.g., “I am firm and calm with him or her”) and two negative (e.g., “I tell him or her off or shout at him or her”) items.
Although face validity for our scales is reasonable and appropriate for the hypothesis-driven nature of the current report, variable internal consistency for these scales was found, with reliabilities lower for scales with fewer items, as is to be expected.
We found across constructs that negative aspects of parenting are significantly more
heritable than positive aspects, again at all three ages. For example, for negative and positive feelings, negative feelings showed significantly more heritability than positive feelings, with average heritabilities across the three ages of 44% and 26%, respectively; the pattern was similar for parental control, with average heritabilities
across the three ages of 27% and 6% for negative and positive aspects, respectively. Finally, creating scales for all the negativity items and all the positivity items regardless of whether they were on the Feeling or Control scale yielded significantly
greater heritability for the negativity than for the positivity, with average heritabilities across the three ages of 44% and 12%, respectively.
For both feelings and control, negativity consistently yielded significantly higher heritability estimates than did positivity, a finding that held for the overall negativity and positivity latent factors (h2 .42 and .10, respectively).
We argue that the “dark” side of genetically driven child characteristics plays a bigger role in eliciting parental negativity than do other child characteristics in eliciting positivity across feelings and control. For example, parental negativity encompassing hostility and harsh parenting may be more responsive to genetically driven challenging child temperament than positive features such as warmth and calmness areto less challenging traits. Distinctions of parenting valence seem to be important for understanding family processes.
One caveat is critical here. In categorizing measures of parenting into positive versus negative valence, we do not include maltreatment. That is, the pattern we report includes aspects of harsh discipline, such as yelling and spanking, but not abusive
forms of parenting. In one study that explicitly looked at this distinction, Jaffee et al. (2004) found that while harsh discipline was moderately genetically influenced (25%), physical maltreatment was not (7%). These findings suggest that children’s genetic influences are largely irrelevant for their vulnerability to maltreatment
and that characteristics of the perpetrator are what are important.
So, one might summarise the findings as saying that when parents deviate into yelling and spanking, it is the genetic characteristics of their children which cause them to do so.