heterogamy

/HH EH0 T ER0 AA1 G AH0 M IY0/
noun
  1. 1

    The state of conjugating gametes that are different in size, structure and function.

  2. 2

    Marriage or similar union between people of different sexes, or social strata, such as races.

Source: https://en.wiktionary.org/wiki/heterogamy