People seem to think there are only identical twin. Born on usually the same day, unless the Labour is long and continues into the next day. They are from one fertilised egg which splits in two and goes on to form two babies (or in the case of other multiple births, more, for instance triplets). Identical twins might not fully seperate in the womb and can end up being conjoined, that is joined together. Sometimes at the head or the body. It is possible to operate and seperate them if they are not sharing organs. This is not always possible though.
There is another form of twin. Non identical. These are two seperate eggs that are fertilised at the same, or almost the same time. Non identical twins are called fraternal twins. They can be a boy and a girl, a boy and a boy or a girl and a girl. They are brothers and sisters born at the same time, but not exact copies. As they grow up their differences become more apparent. They may be bought up wearing the same clothes…. But they are not necessarily the same shape or size. As with identical twins they may have similar interests or completely different ones.
Life can be interesting, a lot of how we live is often influenced by how we are bought up, not just from our genes. It’s the old nurture verses nature argument.