Exploring the Lifetime Effect of Children on Wellbeing Using Two-Sample Mendelian Randomisation

Abstract

Background: Observational research implies a negative effect of having children on wellbeing. Objectives: To provide Mendelian randomisation evidence of the effect of having children on parental wellbeing. Design: Two-sample Mendelian randomisation. Setting: Non-clinical European ancestry participants. Participants: We used the UK Biobank (460,654 male and female European ancestry participants) as a source of genotype-exposure associations, the Social Science Genetics Consortia (SSGAC) (298,420 male and female European ancestry participants), and the Within-Family Consortia (effective sample of 22,656 male and female European ancestry participants) as sources of genotype-outcome associations. Interventions: The lifetime effect of an increase in the genetic liability to having children. Primary and secondary outcome measures: The primary analysis was an inverse variance weighed analysis of subjective wellbeing measured in the 2016 SSGAC Genome Wide Association Study (GWAS). Secondary outcomes included pleiotropy robust estimators applied in the SSGAC and an analysis using the Within-Family consortia GWAS. Results: We did not find strong evidence of a negative (standard deviation) change in wellbeing (β = 0.153 (95% CI: −0.210 to 0.516) per child parented. Secondary outcomes were generally slightly deflated (e.g., −0.049 [95% CI: −0.533 to 0.435] for the Within-Family Consortia and 0.090 [95% CI: −0.167 to 0.347] for weighted median), implying the presence of some residual confounding and pleiotropy. Conclusions: Contrary to the existing literature, our results are not compatible with a measurable negative effect of number of children on the average wellbeing of a parent over their life course. However, we were unable to explore non-linearities, interactions, or time-varying effects.

MRSamePopTest: introducing a simple falsification test for the two-sample mendelian randomisation ‘same population’ assumption

“…Since not all consortia force each study to perform identical GWASs, it could be difficult to compare the methodology to a single study GWAS. However, our applications of this method here and elsewhere to date imply that in practice consortia which use different methods to a single study GWAS, or which do not enforce homogenous methods, do not produce heterogeneous effects from single study GWASs drawn from a comparable population [ 22 – 24 ]. We would however suggest, when possible, triangulating our proposed sensitivity analysis with other approaches, such as a comparison of the measured demographic factors.…”

Family stressors and motivation to have a child versus parental stress of mothers

“…Parenthood is regarded as one of the most important sources of positive experiences in human life (Więsyk, Lachowska, 2020). Apart from studies supporting this thesis, however, there are plenty of those showing that the relationship between parenthood and well-being-not only parents' but also children's-is highly complex and ambiguous ( Jazłowska, Przybyła-Basista, 2019;Nelson, Kushlev, Lyubomirsky, 2014;Piotrowski, Bojanowska, Szczygieł, Mikołajczak, Roskam, 2023;Woolf, Sallis, Munafò, 2023). Moreover, the results of previous research indicate that mothers differ in terms of their parenthood-related experiences (Qian, Mei, Tian, Dou, 2021).…”