Quiz: Remember the definition of mal de mer?
In genetics, a trait that must be contributed by both parents in order to appear in the offspring. Recessive traits can be carried in a person's genes without appearing in that person. For example, a dark-haired person may have one gene for dark hair, which is a dominant trait, and one gene for light hair, which is recessive. It is thus possible for two dark-haired parents to have a light-haired child, provided each parent contributes a gene for light hair.