Allosomal Recessive Gene
Allosomal recessive is a mode of inheritance of genetic traits located on the allosomes (the sex determining chromosomes).
Examples include the gene for haemophilia which is carried on the X chromosome. Diseases carried on the Y chromosome cannot be recessive.
X chromosome diseases are recessive in females unless both of their X chromosomes have the gene. They are not recessive in males because males only have 1 X chromosome so there is not a non-diseased version of the gene to default to.
Read more about this topic: Recessive