Complicated science made simple:

In Chaos Theory, the butterfly effect is the name given to the sensitive connection between initial conditions in which an insignificant event in one state in non-linear systems, can result in sometimes catastrophic events in the universal state.

In other words, although unlikely, it is possible for a butterfly flapping its wings in Texas to cause a typhoon in the Japanese Sea.

Case in point, in mid-20th Century America, an 18 year old hippie freshman in a Honolulu college had sex with an older, alcoholic Kenyan on a student visa, who had a wife and child back in Africa. And this less than significant event started the collapse and dissolution of the United States of America.