Right handedness (R) is dominant over left handedness (r). The ability to roll your tongue (T) is dominant over the inability to roll your tongue (t).

Right handedness (R) is dominant over left handedness (r). The ability to roll your tongue (T) is dominant over the inability to roll your tongue (t). dominant gene is always above recessive gene hence; the organism express the features of the dominant gene

Explanation:

Phenotype reflects the physical expression of the dominant gene of an organism i. e R is dominant over r while the expressive features of genotype R will be physically expressed

Well, i'm not sure what kind of question ur asking, but, capital 'R' refers to a dominant gene, which is more common compared to the recessive gene, (r). so what the passage is trying to say, is that right handedness is a dominant gene compared to left handedness which is a recessive gene. sorry, if this makes no sense to u