Would it be balanced to give Kitsune a natural spell equivilent?

[Liam Warner]

I'm wondering if since a kitsune can take fox shape http://www.d20pfsrd.com/feats/general-feats/fox-shape to shapechange into a full fox form would it be balanced to include as part of that feat a natural spell http://www.d20pfsrd.com/feats/general-feats/natural-spell---final equivilent effect that allows them to cast spells in their fox form (and only that form I.e. if they cast polymorph and shapechanged into another animal they couldn't cast in that form)?

I'm thinking since they're already spending a feat on this form and its essentially a racial ability they unlock spellcaster would be able to cast when in it this is a holdover from 1st ed when the fox was their natural form and the human/hybrid were alternate ones they could take on and I still tend to.think of fox as much a part of their true self as the hybrid/human ones unlike a druid who's learning.over time to copy a particular form but its never their true one which is why a kitsune can be revealed by detect shapeshifter but a druid can't. An opinion reinforced by the fact the fox form they take on is static and always looks the same just like their other ones.

[Toujours]

I don't see it being much of a problem, I would probably roll it into the Magical Tail feat with a special tag that they must take the magical tail feat after getting fox shape to cast in said shape. Mind you that wouldn't preclude them from taking it before the fox shape feat but it would give more of an incentive to take the magical tail feat.

I believe the added natural spell would be a bit too much for one feat but a bit too little on its own.