Sex-Linked Inheritance Basics
Your 23 pairs of chromosomes contain your DNA and genes, with the 23rd pair being your sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). This difference creates unique inheritance patterns for certain traits.
Sex-linked traits are characteristics passed specifically on the X or Y chromosomes. Thomas Hunt Morgan discovered this concept while studying fruit flies (Drosophila). He noticed some male flies had white eyes instead of the normal red eyes, and through careful breeding experiments, he tracked how this trait was inherited differently between males and females.
Sex-linked inheritance explains why certain genetic conditions appear more frequently in males. Since males have only one X chromosome, a recessive gene on that chromosome will always be expressed. Common X-linked recessive disorders include hemophilia (blood clotting disorder), red-green color blindness, and Duchenne muscular dystrophy.
💡 Males are more likely to show X-linked recessive disorders because they only have one X chromosome. With no second X to potentially carry a dominant normal gene, any recessive disease gene on their single X will be expressed.
