Can you asnwer this riddle/joke?

[Joey]

Mary's father has 5 daughters, Nana, Nene, Nini and Nono..Who is the 5th daughter?

 

[Nymphetamine]

It's obviously Mary but I will say Nemo cos I feel like it x

 

[Royal-DLG]

i was expecting a challenge!

mary is the fifth daughter