Ok no worries
From the NHS Choices website:
"Children are able to control their bladder and bowels when they're physically ready and when they want to be dry and clean. Every child is different, so it's best not to compare your child with others.
Bear in mind the following:
most children can control their bowels before their bladder
by the age of two, some children will be dry during the day, but this is still quite early
by the age of three, 9 out of 10 children are dry most days – even then, all children have the odd accident, especially when they're excited, upset or absorbed in something else
by the age of four, most children are reliably dry
It usually takes a little longer to learn to stay dry throughout the night. Although most children learn this between the ages of three and five, it is estimated that a quarter of three-year-olds and one in six five-year-olds wet the bed."
I hope that helps. I think the most important thing is to try and help your parents encourage your lil bro when he stays dry and teach him to put the soiled stuff away in the bin so he learns a little discipline too