Is Biological Link a Cause or Consequence?

In an ideal situation the biological relationship that we have with our (biological) parents or children is a consequence/result of a meaningful relationship; one that goes beyond the physical sexual act of an age-fit couple and expands into a fulfilling and loving one.  This is a point at which we transcend from the sexual attraction and urges inherent in our biological condition and enter into the circle of modern, civilized beings organized into what we know as family.  This ideal situation and condition is a reflexion of our historical jorney as humans as we have been conditioned to form families in which our biological link can be identified and protected.