Speaking of fallacies, how about the one where parenthood increases your risk of underperformance 'exponentially', or is in any way a 'risk factor'. Check your bias. Parenthood is as likely to make you better at your job.
I have met people who were under impression they were performing poorly, but actually they were doing great work. They just were disinterested in the job, which is a different issue.
Have you got any evidence to back that up?