Genes are made of DNA. Strands of DNA strands make up part of your chromosomes. Chromosomes have matching pairs of one copy of a specific gene. The gene occurs in the same position on each chromosome.
Genetic traits, such as eye color, are dominant or recessive:
- Dominant traits are controlled by one gene in the pair of chromosomes.
- Recessive traits need both genes in the gene pair to work together.
Many personal characteristics, such as height, are determined by more than one gene. However, some diseases, such as sickle cell anemia, can be caused by a change in a single gene.