My first two - a boy and a girl were exactly eleven months apart (and the second, my daughter was born absolutely on date). Later on I did have twins - actually much easier than those first two as, at least with the twins, they were doing much the same things at the same time.
For one month each year, my eldest two had the 'same age', much to the delight of my daughter and the often confusion of the teachers at different places who would ask for all the 6-year olds (etc) to stand up, and they both did.
What decade were your grandparents born?
