My sister took an MBTI test on facebook and registered as ISFJ, but I don't think it was all that accurate for her. She is definitely introverted, but is most ways less feeling than most girls. She seems pretty extremely P in some areas and J in others. I'm thinking MBTI is not very accurate for someone being treated for both OCD and bipolar depression. I think her natural type when we were children was INFJ, but that the medications meant to prevent manic episodes leave her essentially unable to use her intuition.
If my half brothers have ever taken such a test they have not told me. I don't know if they would have any real impact on my personality though, as they are much older, never lived with me, and are really more like uncles than brothers. Still, I think I'll venture to guess at their types. I suspect my eldest brother is an ESTJ. He is definitely the most J member of us, and not as intuitive as me. I'm not that confident that he is extroverted, but he is definitely not as introverted as the rest of my father's children. However, his personality is more like my father than the rest of us, so he could be an INTJ who just is not as strong in the I and N categories. I guess he could also be ENTJ, but he seems nothing like any ISTJ I know. (His (second) wife is probably an ISFP.) The younger of my half brothers is definitely introverted and perceiving. I'm inclined to say he is a fellow INTP, but but a less extreme one. He could also be ISTP. (While our personalities may be the most similar, we have very different tastes in women. I prefer INFJs with strong N and reasonably developed Ti. His wife seems very ESTJ. Both sister-in-laws are kindergarten teacher's like their mother, my dad's first wife, who I'd guess is an ISFJ.)