Depends on how you look at it. In America, collective nouns are normally treated as singular. Whereas in Britain (& Ireland) it often depends on whether you see the noun as a unit or as individuals. So if you see your family as a whole unit, then it is 'is'. But if you see them as individuals (i.e. all my family), then you use are. But as I mentioned in my comment, you need to include 'the'. My answer would be: 'My family are from the U.S.' is the correct statement as it relates to all my family and 'My family is American' as it refers to family being singular.