OP, rather than stating that children are anxious, you need to go to the source of that anxiety.
I'll give you a breakdown of why my child is anxious. Two words, her father. He has messed her around and the way he and his vile wife have treated her, is enough to make me break down and sob!
She never showed any signs of anxiety when she was younger. Had he have treated her with the respect she deserved, and not married a woman who thought it was okay to verbally abuse her, things would be very different.
By the way, I didn't know about the VB until a later date, and naturally stopped my child going over there. She made fun of her weight, told her she was ugly..and the very person (apart from me) who she thought she could turn to, went ahead and married her; even though he promised her that they would never get married and that he would put his 'little girl first'.
This has, unfortunately, spilled to other areas of her life, mainly at school.
I have tried EVERYTHING in my power to try and counter all the negativity. But the fact remains, that the one person she thought she could trust, was full of shit and complicit in making her life difficult.
She is just a child. That secure bond that was meant to be there, was broken. She went from daddy's girl to nothing.
This will impact her as an adult. So perhaps you should be asking the same question about adults.
I bet most will trace back to childhood.
Selfish, selfish people (being polite) who are too self-absorbed to realise the impact of their actions.
Thank goodness she has me.