Updated by: Arabinda Naik
Sex-influenced genes are genes that are expressed differently in males and females due to the influence of sex hormones. These genes can have different effects or levels of expression depending on an individual's sex (male or female). The term "sex-influenced" is used to describe genes that are not located on the sex chromosomes (X and Y in mammals) but are still influenced by the presence of sex hormones, such as estrogen and testosterone, which are typically present in different concentrations in males and females. In the case of sex-influenced genes, the same genotype (the genetic makeup) can lead to different phenotypes (observable characteristics) in males and females. This is often due to the interaction between the genetic information and the sex-specific hormonal environment in the body. For example, one well-known case of a sex-influenced gene is the gene responsible for male pattern baldness. This gene is more likely to lead to hair loss in males than in females, even if both have the same genetic variant. The expression of this gene is influenced by the hormonal differences between males and females. Sex-influenced genes are different from sex-linked genes, which are located on the sex chromosomes and show inheritance patterns linked to an individual's sex. Sex-influenced genes can be found on autosomal (non-sex) chromosomes and are influenced by sex hormones.