What are the chance of twins?

My mom was pregnant with fraternal twins but miscarriaged 1. There are two sets of identical on my dads side. I know this doesn't affect me, but my MIL is a fraternal twin and has brothers who are another set of fraternal. Then there's a set of fraternal on my FIL's side too. Twins, twins, and more twins, lol. Probably not going to happen but what are the chances? Anyone else with this many in their fam?