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#sex-influenced traits

2 public questions tagged with this topic.

Horns in sheep being dominant in males but recessive in females is an example of

Sheep horn genetics exemplifies sex-influenced autosomal inheritance. Allele H conferring horned condition acts dominant in males due to testosterone-dependent activation of horn growth pathway, so genotypes HH and Hh males grow horns. Same genotypes in females remain polled because without androgen dominance reverses; only HH females may develop small horns, Hh females stay hornless. Autosomal segregation ratios hold when sexes analyzed separately, not showing X-linked pattern. This clearly contrasts with sex linkage where chromosome location determines transmission, and with sex-limited trai

Ref: Davenport, Sheep Horn Inheritance; Pierce, Genetics Conceptual Approach, Chapter 4: Sex-Influenced Horn Example

Sex-influenced traits differ from sex-linked traits because they are

Sex-influenced traits derive from autosomal genes present equally in males and females, but hormonal environment determines dominance relationship. Androgens versus estrogens alter transcription thresholds, enhancer activity, or receptor sensitivity, making same genotype dominant in one sex and recessive in other. Reciprocal crosses for such loci still produce identical genotypic ratios because autosomal transmission independent of sex, unlike sex-linked traits located on X or Y. Phenotypic discordance arises physiologically, not by chromosome segregation difference, reflecting hormone modulat

Ref: Hartl, Essential Genetics, Chapter 4: Distinguishing Sex-Influenced from Sex-Linked Inheritance