What is genetic dominance?

Genes are sections of our DNA that have a specific genetic code.  When you're born you get a copy of each gene from your mother and a copy of each gene from your father.  These copies are called alleles.  For each gene you get 2 copies of each allele and these can be dominant, receissive or co-dominant.

If you have 2 dominant alleles e.g. RR (red colour in plant), then the plant would be red.

If you have 2 recessive alleles e.g. rr (white colour) then the plant would be white.

If you have 1 dominant and 1 recessive  e.g. Rr then the plant would be red as the dominant allele is always shown.

Incomplete dominance  is where neither allele is dominant e.g. R = red, W = white.  Both alleles are expressed and contribute equally to the phenotype (or colour).  So RR = red, WW = white and RW = pink.

Co-dominance is where both alleles are dominant e.g. Blood Type AB