First, you are born into a family of origin.
Not the one of mammalians or humans. I mean your parents. You may furthermore have siblings and grandparents. Every one of us has parents though. They are the biological precondition for our cheer existences. They have created us. Their act of creation is the prerequisite for your birth. If you read these lines, you are still alive. An important reason for that is the parental care during your first years on this planet. They took responsibility for you. Your needs were more important to them than their own ones. Hence, you want to thank them.
Secondly, you might have founded a family.
It consists of your partner and maybe children. Whether you are married or not: If both of you decided to spend your life together, this very promise creates an invisible relationship string between you. It can have a similar strength than the ones to your parents or siblings yet always have a different quality.