Which of the following is not a hereditary disease
Cretinism
Cystic fibrosis
Thalassaemia
Haemophilia
Coupling and repulsion are the two faces of
Definitions / Explanation : Epistatic Gene or Inhibitory Gene
$A$ : The heterozygotic female for haemophilia may transmit the disease to sons.
$R$ : Such traits show criss-cross inheritance
When a cluster of genes shows linkage behaviour they
Genes that are similar in phenotypic effect when present separately, but together interact to produce a different trait and ratio is $9 : 7$ in $F_2$ generation. What are such genes known as