User blog comment:BluJayPJ/When it comes to birthdates/@comment-30243207-20161016123933

As mentioned, because Gumball had been 12 for about 5 years now, it is really undetermined. But this is what I think:

Gumball is born in the 2000s

Darwin is 9 years old, so it could be 2004s

Anais is about 4 years old, she could be born in 2007s

Nicole is 38 years old, she could've born in 1980s

Richard is about 40 years old, so he could been borns in 1975s

That's what I think :)