3 public questions tagged with this topic.
Dominant traits are not necessarily more common; frequency depends on factors like natural selection and genetic drift.
Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Chromosomal Theory Linkage Recombination Gene Mapping
X-linked dominant allele located on X chromosome expresses phenotype even in heterozygous female. Affected father X^A Y transmits X^A containing dominant allele to all daughters via X-bearing sperm, making every daughter affected regardless of maternal genotype, while sons receive paternal Y and are unaffected unless mother also carries trait. This father-to-all-daughters transmission pattern is hallmark of X-linked dominant pedigrees, distinguishing it from autosomal dominant where father passes trait to half offspring irrespective of sex. Affected mothers pass trait to half sons and half daughters.
Ref: NCBI Bookshelf, Hartl, X-linked Dominant Inheritance Patterns and Pedigree Features
Trihybrid cross AaBbCc x AaBbCc with independent assortment and complete dominance at each locus involves three independent segregation events. Probability offspring receives no dominant allele, i.e., homozygous recessive aabbcc, equals product of individual recessive probabilities (1/4)*(1/4)*(1/4)=1/64. Complementary event showing at least one dominant trait therefore equals 1 minus all recessive probability, 1-1/64=63/64. Calculation employs product rule for independent events and complement rule for union. Includes classes expressing one, two, or three dominant phenotypes, useful for predicting proportions in multigenic traits.
Ref: Griffiths et al., Introduction to Genetic Analysis, 12th ed., Chapter 2: Probability Rules for Trihybrid Cross
