Genetics inheritance

Genetics is the science of genes, heredity and the variation of organisms. Molecular genetics build upon the foundation of classical genetics but focus on the structure and function of genes at a molecular level. Molecular genetics employ the methods of both, classical genetics and molecular biology. A more recent development is the rise of genomic, which attempt the study of large-scale genetic patterns across the genome for (and in principle, all the DNA in) a given species. The field typically depends on the availability of whole genome sequences using bioinformatic approaches for analysis of large sets of data.
	The genotype (the genetic configuration; the primary genetic information) characterises an organism as individual. But phenotype (appearance; sum of all notable attributes of an organism), development and biological fitness of an organism are determined by many more factors than only the genotype. On one hand, a wide plasticity of expression and regulation of the genome has been observed, on the other hand, external, environmental influences such as nutrition, lifestyle (behaviour) or harsh conditions (temperature, toxins, starving, etc.) shape the phenotype of an organism. Both, genetic aberrations and the factors mentioned can trigger diseases.
Many of these conditions cause common health problems while others are rare. Common health problems include some forms of cancer, cardiac diseases, diabetes and mental illness such as schizophrenia and manic depression. These influences are called "multifactorial" and do often interact synergistically. Multifactorial inheritance (MI) refers to the pattern of inheritance, passing through the generations of a family, of conditions and characteristics that are due to an interaction between an individual's genetic make-up and environmental factors. Although MI tends to "run in families", it is less predictable than mutations, genetic alterations at the level of the genotype.