2.21 : 遗传

Gregor Mendel's principles of inheritance demonstrated how traits are transmitted from parents to offspring and are controlled by distinct units known as genes, which exist in pairs within organisms.

A genotype, the unique combination of genes inherited from both parents, determines potential traits such as eye color, height, and susceptibility to certain diseases.

In contrast, the phenotype, which includes observable traits, can differ from the genotype due to environmental factors such as nutrition and climate.

For example, adequate nutrition is crucial for reaching potential height.

In many cases, gene expression can be dominant or recessive. Dominant genes overshadow the effects of other genes, while recessive genes only express themselves in the absence of a dominant gene.

For example, a child can inherit blue eyes – a recessive trait – even if both parents have brown eyes, a dominant trait, provided each parent contributes a recessive gene for blue eyes.

Conversely, psychological traits do not follow simple dominant or recessive patterns and are influenced by numerous genes, each exerting a small effect, such as in the case of schizophrenia and bipolar disorder.