When two events (call them A and B) are Mutually Exclusive it is impossible for them to happen together: P(A and B) = 0. The probability of A and B together equals 0 (impossible).
Answer Wiki. Strauss & Howe, the social historians known for pioneering generational theory[1], would say that Gen X (the 13th generation) and Gen Y (the millennial generation) each have the traits of their corresponding generational archetypes. Generation X is generally used to refer to people born in the 60s and 70s. According to Strauss & Howe, it is a Nomad generation, an archetype they share with the Lost Generation of the 1890s and 1900s. Both generations are characterized by a disaffected attitude and general disdain for everything that came before.
Generation Y refers to the population group in the US born from somewhere around 1976 to around 2000. They are sometimes called echo boomers because some of them are the children of baby boomers. On the other hand, some Generation Y children, especially those born in the late 1980s or afterwards, may be the grandchildren of baby boomers. Other names for this group are the Millennials, the Internet Generation, and the abbreviated Gen Y or Gen Yers.