Well Thank you all. I did have a nice Birthday. One more card than expected, presents from my DH and DCs and a lovely meal out. But the day ended on a sour note when I noticed that none of my DGC had acknowledged my birthday, not even a quick message on Facebook. They are all teenagers so I expected their parents to give them a nudge. So at the end of the day I put it on facebook. Along the lines of "Thank you for all your kind messages but not one from my grandsons". I sat back waiting for "Sorry Nan, Happy Birthday". Did that happen, no it didn't. My one daughter got herself in such a fury at me "humiliating" her sons that she unfriended me on facebook and blocked me. [shock}
Perhaps I have gone onto another topic with this. However, it was such a shame when my birthday was going quite well and I was happy.
I can't imagine not wishing my own grandmother a Happy Birthday, probably with a nudge from my mother. And I certainly wouldn't have unfriended and blocked my mother if such a thing were possible in those days. I acknowledge all their birthdays, with presents and latterly with £50 each in a carefully chosen birthday card. 
Any comments, especially how to proceed with one grandson's eighteenth birthday coming up fast!!