My son is six years old and he's quite a quiet little thing. He's a bit of a worrier and although he has friends at school he's prone to keeping himself to himself. He's certainly not as full of beans as his older sister (she's nine now) was when she was his age. There's no reason that I can put my finger on for why he's this way but any advice will be gratefully received.

The emotional development of your child is a key to her future happiness, as well as a cornerstone of well-regulated behaviour, writes Dr Stephen Briers in his book Superpowers for Parents, The psychology of great parenting and happy children.

My son aged nine has started throwing strops and is taking much longer to come out of them than ever before. He wouldn't play with his four-year-old sister at her party and when I told him he was being selfish, he took a huge huff and stayed in it for nearly an hour. I got angry with him, threatened sanctions, tried being nice - pretty much everything - but all to no avail? Any ideas?