Human beings have two sex chromosomes – X and Y . Males have XY and females have XX. Y chromosome have some male specific genes ….but the x chromosome have copies of many genes which the Y chromosome is lacking and a major portion of Y chromosome is considered genetically INERT.
Thus females have two gene loci available on each X chromosome and males have only one gene locus on one X chromosome ( as the other one is Y chromosome) .
In females , the expression of sex linked trait is when it is Dominant …or if it is Recessive …then female needs to be Homozygous for it .
Whereas in the case of Males… the allele present on X chromosome will be directly expressed whether it is Recessive or Dominant ..because males have only one X chromosome .
Thus X linked traits are more frequently expressed in males than in the females.