True. I'm good friends with a pair of identical twins and cousins with another. Other than resenting each other in teenage years, both pairs are extremely close and share very similar interests. This could potentially be because of genetic factors or because of a very close bond caused by their identical twin status that leads to the incredibly similar environment, closer than most siblings, that leads to such similarities.

The only way to truly isolate whether these are result of identical DNA or identical environments would be an incredibly inhumane method involving separating twins at birth and giving them radically different environments to grow up in to determine how the different twin-trends hold up when that variable is isolated. It is unfortunate that identical twins give us the potential to almost explore different timelines for one person by taking the same starting point down different paths, but only through incredibly tedious, inhumane, and life determining methods.

It's almost like nature is taunting us