Genes or genetic mean something
related to your DNA. Hereditary means something you
inherit from your parents.
When kings die their
child inherits the throne. That is hereditary, but it is not
genetic, because there is no gene that makes a person royalty.
Not all genetic
conditions are hereditary, such as if they are caused by a
mutation they will not have been inherited.
Bottom Line, DNA is
inherited, so genetic medical conditions are hereditary, but not
all hereditary things are genetic.