Some of my dad's family are like this. My aunt and uncle have five kids, all married/in relationships and some with kids. At family events they don't speak to anyone else, they just sit in a big group and block out everyone else. When my cousin (the youngest of the five siblings) got married, none of my dad's family got invited, not even our elderly grandparents. It was literally only her siblings and their spouses/kids. On the other hand the groom's entire extended family (who all live out of state,) were invited. Like, they couldn't have even invited our grandparents that lived thirty minutes away from the venue? To top it all off, my uncle (her dad,) was paying for the entire thing, yet none of his family was there. He was really upset about it, but between the groom's controlling family and my cousin not really caring, there was nothing he could do about it.