moniperiytymistä

Moniperiytyminen, or moniperiytymistä in the form used for discussion, is a term used in genetics to describe a mode of inheritance in which a trait is transmitted primarily by a single gene locus. The word combines mono- meaning one and periytyminen meaning inheritance. In many Finnish genetics sources, moniperiytyminen is treated as aligned with monogenic (single-gene) inheritance, where alleles segregate according to Mendelian principles.

Key features of moniperiytyminen include the presence of distinct alleles at one gene locus with dominant and recessive relationships, and the expectation of relatively predictable phenotypic ratios in offspring from monohybrid crosses. Traits influenced by a single gene can show complete dominance, incomplete dominance, or codominance, and they often yield clear genotype–phenotype correlations.

However, most real-world traits are more complex. Limitations of simple moniperiytyminen arise from incomplete penetrance, variable expressivity, pleiotropy (a single gene affecting multiple traits), epistasis (gene interactions), and environmental influences. Consequently, many traits that appear to run in families do so through polygenic or multifactorial mechanisms rather than true single-gene inheritance.

Applications of the concept include genetic counseling, medical genetics for identifying Mendelian disorders, and plant or animal breeding where single-gene traits are targeted for selection. Understanding moniperiytyminen provides a foundational contrast to polygenic and multifactorial inheritance and helps frame more complex inheritance patterns.