Traits Ear lobes Hair on fingers Widows peak

Traits

Ear lobes

Hair on fingers

Widow’s peak

Hair curl

Cleft chin

Smile dimples

Roll tongue

straight thumb curved straight

pinky

Hand clasping

• The dominant trait is for lobes to hang free, a bit of lobe hanging down prior to the point where the bottom of the ear attaches to the head. With the recessive phenotype, the lobes are attached directly to the head. Alleles: F. f • Dominant phenotype: free lobes • Dominant genotype: F – • Recessive genotype: ff

Mid-digital Hair • Some people have hair on the second (middle) joint of one or more of their fingers, while others don’t. Having any hair at all means that you have the dominant phenotype. • Complete absence of hair is recessive. • Alleles: H, h • Dominant phenotype: hair on skin finger’s second joint • Dominant genotype: H – • Recessive genotype: hh

• Widow peak is dominant • Straight hairline is recessive

• Curly is dominant and homozygous • Wavy: heterozygous

• Dark hair is dominant • Blonde hair is recessive • Red hair is recessive

Chin Cleft • A prominent cleft in the chin is due to the bond structure which underlies the Yshaped fissure of the chin. Females appear to be less conspicuously affected than males. Alleles: C, c • Dominant phenotype: cleft present • Dominant genotype: C – • Recessive genotype: cc

Facial Dimples • If you aren’t sure if you have them, smile! Dimples are easiest to see when smiling. With dominant phenotype, you may have a dimple only on one side, or on both. • Alleles: D, d • Dominant phenotype: dimples present • Dominant genotype: D – (the dash means the genotype may be either DD or Dd) • Recessive genotype: dd

• Ability to roll your tongue is dominant.

• Straight thumb is dominant • Hitchhiker’s thumb is recessive

Bent Little Finger • A dominant allele causes the last joint of the little finger to dramatically bend inward toward the 4 th finger. Lay both hands flat on a table relax your muscles, and note whether your have a bent or straight little finger. Alleles: B, b • Dominant phenotype: bent little finger • Dominant genotype: B – • Recessive genotype: bb

Hand Clasping • Clasp your hands together (without thinking about it!). Most people place their left thumb on top of their right and this happens to be the dominant phenotype. Now, for fun, try clasping your hands so that the opposite thumb is on top. Feels strange and unnatural, doesn’t it? Alleles: L, l • Dominant phenotype: left thumb on top • Dominant genotype: L – • Recessive genotype: ll

Eye Color • We’re kind of cheating here. Eye color, as well as hair and skin color, is a complex trait. Not a case of simple inheritance. The main pigment is melanin, and the more melanin, the darker the color. • Although the genetics of eye color is complex, alleles for the production of melanin dominate those for lack of melanin. So if we evaluate eye color as being blue (recessive) or non-blue (dominant) we can treat it as a characteristic of simple inheritance. • • Alleles: E, e Dominant phenotype: non-blue eyes Dominant genotype: E – Recessive genotype: ee

Interesting: • • • Freckles are dominant Long eyelashes are dominant Broad lips are dominant Immunity to poison ivy is dominant Farsightedness is dominant to normal vision.