Answer:
Everyone has a family tree in the sense that everyone who ever lived had parents, grandparents, great grandparents, etc., and most also had siblings, aunts and uncles, nieces and nephews, etc. Sacagewea is no different in that regard.
Because she came from a culture that did not put great emphasis on written records, much of her family history is not known. What is known is that she had two children, once of whom lived long enough to have a son who died as a child in Europe.
The Wikipedia article on her can be helpful in learning what is known of her and her family. See the related links below.