What activities cause cultural blending to occur?

There are many possible activities. One very common and mundane one is when a man and a woman or two men/women from differenrt cultures get together and either become a couple or married. Both bring their culture into the relationship. Over time, they both discard parts of their own culture and take on parts of the culture of their spouse, this is how a new culture is then born and you have a mixed/blended culture.