Identical twins are sometimes called "monozygotic" twins. Each baby will have the same genes. Identical twins are therefore the same sex – both boys or both.
It turns out that it's not only genetics that matter, but also the type of twins being discussed. In my family, the most recent set of twins was.
Find out whether the tendency to conceive twins is an inherited trait that runs in A man who carries the gene doesn't have a greater chance of having twins.