Is having twins or multiple children at the same time a hereditary trait?!?!?

People have always said that twins can be hereditary...however, I don't know how much of this is actually true because it has been shown that older women have a higher chance at having twins than younger women...so I wonder how many twins come from older mothers...but sometimes, it just happens and sometimes it doesn't. My friend's mother is a fraternal twin and my friend had 3 single pregnancies...so you never know