Madam, – Once again a survey mistakes correlation for cause. An ERSI study Family Figures: Family Dynamics and Family Types in Ireland 1986-2006, cited in an article (Front page, February 23rd), notes the correlation of having one child and marital breakdown. It assumes cause based on that correlation. Perhaps it's just that couples tend have one child in their initial years of marriage and the marital breakdown also tends to happen in that same early period.
Your Editorial even notes that, counter-intuitively, the arrival of a second child sees a decrease in the likelihood of marital breakdown.
It is akin and as logical as the argument that smoking is a remedy for Alzheimer’s disease: smokers die prematurely; Alzheimer’s disease occurs later in life and so smokers are less likely to contract it; therefore smoking is an obvious cure! – Yours, etc,