My family has a lot of twins, I was one, but my twin died young, my sister has twins, my grandfather was a twin, and I have twin cousins. Most of them are more than normally close, but my cousins re always fighting and arguing. As adults they only see each other at family functions, wedding and funerals. Those who are close are quite remarkable in their ability to “synchronise” in thought and action, even when apart. They will choose the same clothing, watch the same shows, eat the same food.