-Genes located on or other of the sex chromosomes are said to be sex-linked
-They are located on the unpaired part of the X-chromosomes in males
-They always show their effects on the heterogametic sex offspring(males) because there is nothing on the Y- chromosomes to counteract their effect.
-Females are commonly carriers of trait.
-These carriers can transmit there effects  to their male children.
-There must be a double dose of the alleles (one from the father and one from the mother) before it can be manifested on the phenotypically or show effects in female offspring.
-Five genotypes are usually presents.
-Examples include; haemophilia, baldness in man, colour blindness, white eyes in drosophilia