In what ratio does a child inherit their father's and mother's genetic traits?

Children inherit genetic traits from both parents in a specific manner, but the concept of a simple ratio for all traits is not entirely accurate. Here's how it works:

1. Genetic Inheritance Basics: Each child inherits 50% of their genes from each parent. This is because each parent contributes one allele (a variant of a gene) for each gene pair. The combination of these alleles determines the traits expressed by the child4.

2. Mendelian Inheritance: For many traits, Mendel's laws apply. In a simple case, if a trait is determined by a single gene with two alleles (one dominant and one recessive), the offspring can inherit the dominant allele from either parent and still express the dominant trait. The genotypic ratio for offspring of two heterozygous parents is 1:2:1 (homozygous dominant, heterozygous, homozygous recessive), but the phenotypic ratio is often 3:1 (three dominant to one recessive)15.

3. Complex Traits and Epigenetics: Many traits are influenced by multiple genes and environmental factors. Epigenetics also plays a role, where the expression of genes can be influenced by the parent of origin. Some studies suggest that genes from the father might be more active in certain contexts4.

4. Mitochondrial DNA: Children inherit all their mitochondrial DNA from their mother, as only egg cells contribute mitochondria to the zygote2.

In summary, while children inherit 50% of their genes from each parent, the expression of traits can vary due to dominance, epigenetics, and other factors. There isn't a single ratio that applies universally to all genetic traits.