Certain traits follow clean, predictable ratios. Mendelian inheritance describes patterns of transmission that obey Mendel’s laws of segregation and independent assortment. Single-gene traits with clear dominant or recessive relationships are the classic examples.

Autosomal dominant, autosomal recessive, X-linked, and Y-linked patterns are all Mendelian when a single locus is responsible. Pedigrees reveal these patterns through the distribution of affected individuals across generations. Molecular confirmation identifies the causative gene and variants.

Not all inheritance is Mendelian. Polygenic traits, incomplete penetrance, and environmental influences produce more complex patterns. Nevertheless, Mendelian principles remain the starting point for analyzing family data and calculating recurrence risks in genetic counseling.

• Inheritance following Mendel’s laws
• Applies to single-gene traits
• Includes dominant, recessive, and sex-linked patterns
• Visible in pedigree analysis