Inheritance and recessive traits
- Remember that for most genes, you have two copies of each gene that you inherited from your mother and your father.
- Each copy of the gene could be different. For example one copy may give you blue eyes while another may give you brown.
- So, what color are your eyes if you have both the brown and blue eye version of the eye color gene?
- Brown. This is where the idea of dominant and recessive comes in. The brown version of the gene makes a pigment that turns your eye brown but the blue version does not make a blue pigment. Instead, it makes no pigment and an eye without pigment is blue.
Dominant means that one of the versions trumps the other.
- There are two “hair type” genes, curly and straight. If you have two copies of the curly version, you have curly hair and if you have two copies of straight hair version, you have straight hair.
- Each of these versions contributes something so that you get a mixture of the two. You would write this out as CC is curly, SS is straight and CS is wavy.
Bent pinky:
- The dominant version of the gene causes distal segment of pinky finger to bend distinctly inward toward the ring (fourth) finger.
Tongue rolling:
- People with a dominant allele can roll their tongues into a tube shape. People with two recessive versions are non-rollers and can not learn to roll their tongues.
Ear lobes:
- Recessives have attached ear lobes. People with a dominant version of the gene have detached ear lobes.
Thumb crossing:
- In a relaxed interlocking of fingers, left thumb over right results from having 1 or 2 copies of the dominant version of the gene. People with 2 recessives place right thumb over left.
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