It seems that every second adult on MN suffers from anxiety too, so it’s hardly surprising that the next generation will - either through learned behaviour or by their parents instilling fear/anxiety into them about perfectly normal transactions.
Or actually, some of us with anxiety are working hard so our children are confident and empowered and more secure. What a load of 
I suffer from anxiety. I have suffered from it from the age of 6, probably earlier. I didn't know it because back then it was a matter of "pull yourself together" I got no support whatsoever. That lead to eating disorders and so on, the list goes on. I always thought I was crazy and should just die.
Until I was told that actually, what happens to me happens to many and that it is not my fault, and they gave it a name, anxiety.
I am not blaming my parents for it, I think it is a combination of factors.
I also think there are more cases now because of the way society has changed and that we are more aware of it, so maybe numbers haven't doubled, but increased a bit and so has our awareness of it.
To those that are suggesting it is because children are too protected or not given challenges, I suggest you read some evidence based studies. This is not the case.
I was given plenty of experiences. I was also raised to do my own thing and I was academically successful. I had to be tough though, and never really experience close contact with my parents, hugs or things like that.
Anxiety can't be decipher by Google, even professionals are trying to get their heads around how it all works.