Rahu and Ketu are always associated with our family genes. Basically it is said that our family karma are passed on to us in DNAs we obtain from our maternal and paternal families.
Rahu shows the Father side whereas Ketu shows Mother side DNAs. Also Rahu is associated with Paternal Grand Parents and Ketu with Maternal Grand Parents. Even science now says that kids get the properties more from Grand Parents than parents.
Rahu and Ketu contains the secrets of past lives, family history and related Karmas in form of DNA
If we draw the full path of Rahu and Ketu we get something which looks very similar to DNA threads intermingled. Also we know that Sun and Moon create the Rahu and Ketu, much like how DNAs are passed from parents to child.