Another aspect to consider is that once chromosomes pair off, some genes are more dominant than others. For this reason, a particular trait might not show up on the phenotype (physical appearance or trait showing up on a child born) but be carried latently, only to show up again in a following generation (when not "outdone" by a dominant gene). This latent or invisible genetic code is called the genotype.
Sometimes (eye colour being an example) there is not an arbitrary "all or none" principle at work but a sharing of the two traits going on. For this reason, a blue-eyed (recessive gene) man and a brown-eyed (dominant gene) woman may have a hazel or green-eyed child.
Other traits are known to be sex-related or sex-linked. For example, baldness is usually a masculine trait but is inherited by the phenotype's mother. Other traits more prevalent in (but not always so) the male sex are colour-blindness, haemophilia, and even dyslexia. This is because the X chromosome (carried by the female)is physically more "complete" than the Y(carried by the male).
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