Vatican City's Population
Vatican City if full of many traditions, cultural influences, and most of all catholic culture. But there are several things about how Vatican City handles migration that has a huge cultural impact. Most migrations are into Vatican City rather than out. And to get into Vatican City to be a citizen, you have to have a high power in the Catholic Church. Also, Females are not allowed to be citizens in Vatican City so reproduction isn't an option. Culture diffusion is never seen in Vatican City because Vatican City was founded to be the base or head of the Catholic Church thus meaning that Catholicism has already spread and will always remain as long as Vatican City is run the head of the Catholic Church.
The weird population pyramid of Vatican City
Sources
Migration States: http://www.thesocialcontract.com/artman2/publish/ /article_473.shtml
Cultural Diffusion: http://www.vaticanstate.va/content/vaticanstate/en.html
Cultural Diffusion: http://www.vaticanstate.va/content/vaticanstate/en.html