Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-69.121.172.69-20130820040029/@comment-190.222.75.8-20140212022426

The word "shapeshifter" mean that can be a varity of types (werewolf, werecoyote, kitsunae, etc), as well of variety of forms for each type (for example the different werewolf's forms: Peter, Deucalion, Talia and the Kanima); from what I understand from the show, the form depends of power, personality and control.

In case of werewolfs: -Few control = beastly like Peter, -Extra Power+control+sadistic personality = strong and monstrous like Deucalion, -Standard caracteristics = standard form, -Control+balanced personality = full wolf form.

Well I seriously believe full wolf form is not only a Hale thing, but a caracteristic more likely in females werewolfs. I mean, wolfs are know for being very controlled animals and great leaders ...and as well Argent's family's story tells: women are more controlled than men, so they are better as leaders. Then, women are more likely to qualify to full wolf form. Talia Hale was a leader, that's why she could become full wolf (we can assume Derek's sister too).