Driving gestures

Driving gestures could make you think of anything really but one issue is starting to bug me.  When I am driving down the road and another driver kindly lets me pass, I do try and say thank you with a swift raise of my hand.  Sometimes I have been known to forget due to children arguing in the back or the use of my hands trying to drive.  The other drivers then seem to take it on themselves to shout obscenities or raise their hands in rude gestures as I pass.  This of course makes me react badly!

It happened again this morning and I thought, well hang on, according to the Highway Code, I do not have to say anything.  Usually one side or the other has the right of way and in other cases it is down to individual incidents.  So why does everyone feel obliged to thank everyone?  And if a driver cannot say thank you, why does the driver assume it is then OK to be rude?  You have no idea why they did not gesture thanks even though they do not have to.  Why do we as drivers feel we need that?  Is that all our insecurities coming out?  Wanting and needing that recognition that we did a nice thing and let someone pass through?

I am all for thanking as and when, but when I am unable, I should not be made to feel bad nor should I get angry at someone as they decided they should direct their anger at me for not rubbing their ego.  Opinions wanted on this one.  Should we all just calm a little on the roads??