Answer 1
There is a large amount of cultural overlap between the two regions.
Also, there is no natural physical boundary between Europe and Southwest Asia. Unlike most other continents, which are distinct land masses, Europe and Asia occupy the same land mass--Eurasia.
Several countries have cultural elements from both regions.
Answer 2
People from Southeastern Europe and Southwestern Asia actually have a very clear sense of what countries belong to which continents and can clearly point out whether a country is Asian or European. There are only two countries with overlap: Turkey and Cyprus. Turkey is considered to be both European and Southwest Asian, although it is culturally distinct from both. The Bosporus and Dardanelles Straits are considered the border between Europe and Asia and run right through Turkey. Cyprus is considered culturally European but part of the Asian continent.