traits

Traits are attributes or characteristics of an organism, system, or object that can be observed or measured and help distinguish it from others. In biology, a trait can be physical (phenotype) or genetic, and traits vary within and between populations due to genetic variation and environmental influence. Genetic traits arise from alleles at one or more loci and may be Mendelian, controlled by a single gene, or polygenic, influenced by many genes with additive effects. Environmental factors, developmental processes, and epigenetic modifications can modify trait expression even for the same genotype.

Traits are commonly categorized as discrete or continuous. Discrete traits have categories (blood type, in some cases), while continuous traits show a spectrum (height, skin color). Heritability is a population-level concept describing how much of observed variation is due to genetic factors, not a measure for individuals.

In psychology, traits refer to enduring patterns of thoughts, feelings, and behaviors, forming the basis of personality trait theories such as the Big Five. In ecology and evolution, traits influence fitness and adaptation, and natural selection acts on trait variation, often involving trade-offs.

Measurement and analysis of traits underpin breeding programs, medical genetics, and psychological assessment. Trait data are collected through observation, experimentation, and molecular techniques, and interpreted with statistical models to separate genetic and environmental contributions.