Although this seems to be over, I can’t help noticing just how different the concepts you two discussed were - completely unrelated issues.
Physical consequences of sin are not the same as some sort of a curse or sins migrating from parents to children or even spiritual damage to the child.
If you, for instance, leave your child alone in the crib all day long (I know a mother who did this on advice from a midwife

) and later realize this was wrong and repent (the mother did), the child will still have been affected by this in different ways.
And of course children *are *affected by being left alone by their parents for extended periods of time, even if they are too young to remember it. Children are affected by all sorts of things they don’t remember. We don’t give them enough credit. People used to believe babies didn’t feel pain, so even surgeries were sometimes done on infants without anesthetics. Those same infants often had phobias related to white coats and hospitals when they grew up.
We tend to dehumanize the youngest and most vulnerable of us.
And research has shown that, yes, those first 40 or so hours of life outside of the mother’s body do impact the developing embryos. These effects are not necessarily all negative, and the negative ones aren’t dire, but they’re there. One of them, for instance, is that IVF babies tend to be less cautious and careful, and another that they tend to be slimmer. Both these effects have been attributed to the early environment.
Can’t we find a way to acknowledge that the things that happen and we do have effects without simultaneously inducing eternal non-productive guilt-trips that make people infer someone doesn’t believe in the effects of baptism and confession and whatnot?
My first baby was separated from me for almost ten days because of what I believe was a silly reason (fear of an impending infection). If I’d gone to a different, smaller, more relaxed hospital, they probably wouldn’t have even tested her for this. We have both been seriously affected by this separation. Acknowledging this helps - it doesn’t paralyze us forever.
Raising my voice at my children and once even spanking my daughter out of frustration has impacted us all, even after I have confessed it.
Sometimes we just can’t see the effects of out actions immediately.