They imagine a grand career in some profession their child has zero talent for. They expect a dull, routine lifestyle for a child who is clearly rebellious and quirky. They hear the patter of tiny feet when their child has no desire whatever for an infant.
I've known so many people who say their parents don't understand them, don't appreciate what motivates them, and constantly undermine their true aims and ambitions. In short, their parents are more of a hindrance than a help.
Is it so hard to see your children as they are and encourage them in their true inclinations rather than a load of parental daydreams?
When I was young my mother and father had endless preconceptions about what sort of person I was and what I should do with my life, and they always found the reality hard to adjust to.
In the few years that I worked for a local paper, they saw me as some high-flying journalist jetting around the globe reporting world-shattering events. But it wasn't what I was cut out for or interested in.
They assumed I would share their very orthodox political views, and were baffled and upset when my views got increasingly left-wing and iconoclastic.
They expected me to have children and grandchildren, and couldn't understand why I opted out.
In general they saw me as Mr Normal, following a predictable, conventional, conservative lifestyle, probably on some new-build suburban estate where everyone mowed the lawn on Sundays and changed their car every three years.
I think they were permanently shell-shocked by my turning into the exact opposite of their stifling stereotypes. They looked on in disbelief as I adopted one radical cause after another - homosexuality, feminism, socialism, vegetarianism, premarital sex and abstract art, to name but a few. They probably wondered if some hospital blunder had left them with someone else's baby. They certainly saw me as as some alien being from another planet.
It must be very heaven to have parents who truly appreciate you for what you are.
