I've seen "no tiene por qué" translated at
http://context.reverso.net/traduccio...+tiene+por+que as "doesn't have to".
Willow... no tiene por que ser así.
Willow, it doesn't have to be like that.
Pero no tiene por que limitarte.
But it doesn't have to limit you.
Él no tiene por que saber.
We don't have to tell him.
Would a more literal translation of "no tiene por qué" be "(He/she/it) has no reason to"? And a looser translation might be "doesn't need to"?
Are there any instances where the two meanings overlap? That is, there is "no need for something" because there is "no reason for it"?