Genetic bonding
Genetic bonding was a Betazed tradition, a type of arranged marriage. 

The tradition involved vows, and bonding gifts, which were akin to wedding presents.

Deanna Troi was genetically bonded with the Human Wyatt Miller, whose father was the closest friend of her father. The marriage did not ultimately go through. ()

See also
Telepathic mating bond
culture
Medical conditions