Banana is a fruit of the genus Musa.
Genetics
Almost all banana sorts lack genetic diversity, which makes them vulnerable to diseases.
Gros Michel was the main variety of banana grown. The artificial banana flavouring is based on its flavour. However, due to the Panama disease, many plantations were wiped out, so they had to switch the sort. This is the reason artificial banana flavouring doesn't taste like actual bananas.
The current most widely popular banana variety, Cavendish, may suffer from the same fate. There are, however, hybrids of Cavendish and Gros Michel that may be resistant to the Panama disease. There are also efforts to genetically modify these varieties.