I think that a family makes a family - you don't have to be blood related to be a 'real' family in a lot of cases - and the same goes for people who are blood related.
My parents divorced when I was 11 and I find my mom and I were more of a family then than ever before. So, I suppose the answer to your question is dependent on your own personal definition of "Family". Does it mean 'blood relatives"? - if so, nothing can change that, not even distance. If it means "people close to you", then you will always have family in those you love, no matter their blood relation to you.
If both parents are active in the child's life, then they are both family to that child. Families are much more fluid and expandable now than the traditional families of the past!