The question implies that the "generation gap" is the fault of either old or young people. You might want to consider that the issue is whether the experience of the former makes it impossible for them to relate to the experience of the latter -- and vice versa.
Think of all the things that are important to young people -- music, clothes, TV shows, movies, art and so on.
Those things were important to older people, too, when they were younger. It's just that there was different music, clothes, TV shows, etc.
Other important issues to young people might include environmental concerns and social issues.
Older people are interested in those things, too, but their interests are influenced by what they've already experienced. Someone who's experienced World War II will have a different attitude to the war in Afghanistan.
Imagine how a young person might view a vegan diet and compare that to the view of an older person who might have dietary issues and may not be able to tolerate certain foods.
In other words, we tend to view the world according to the limits of our experience.
Going back to your question, now try thinking of a way to frame a thesis that would address the issue of experience, instead of merely blaming one group or another.