simply because they attend to the needs of their family/children and they're females and therefore "feelers". It's a common misconception. (and I mostly mean MBTI but it would translate to any other personality "test" out there, which is testing those dichotomies).
I was in a group this afternoon where the ISTj and the INTj both think they're ISFj. And they're not. It's interesting. Also, there's an ENFj who thinks she's ESFj.