Thanks brother, for this lovely reminder to parents, and will-soon be couples.
Well, I think there are lots of factors tied to raising up beautiful kids, whose ways are patterned by God's word. However, one of the reasons why most parents have failed unknowingly in this regard is IMBALANCE.

Sound ambiguous, right?
Yes, most parents get carried away by their jobs, ministry, occupations, carriers... (give it whatever name you want!) And they forget or become negligent about their parental duties to their kids. Eli was no exception.
In other words, life is about balance. And even God's word support it, when it days "Let your moderation be known to all men" (Philippians 4:5)