Season 1 of Friends aired from September 22, 1994 to May 18, 1995 on NBC in the US. This season introduces the six main characters: Rachel Greene, Monica Geller, Phoebe Buffay, Joey Tribbiani, Chandler Bing and Ross Geller.. The 23rd chromosome is known as the sex chromosome. As with the other chromosomes, one is inherited from the father, and one from the mother. The 23rd chromosome from the mother is always an X. From the father, a person either inherits an X chromosome or a Y chromosome. The chromosome inherited from the father determines their gender..