If earlobes hang free, they are detached. If they connect directly to the sides of the head, they are attached. Earlobe attachment is a continuous trait: while most earlobes can be neatly categorized as attached or unattached, some are in-between.
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Some people can curl up the sides of their tongue to form a tube shape. In 1940, Alfred Sturtevant observed that about 70% of people of European ancestry could roll their tongues and the remaining 30% could not.
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Dimples are small, natural indentations on the cheeks. They can appear on one or both sides, and they often change with age. Some people are born with dimples that disappear when they’re adults; others develop dimples later in childhood.
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Overall, about 10% of people are left-handed, but the number varies among cultures from 0.5% to 24%.
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Freckles show a dominant inheritance pattern: parents who have freckles tend to have children with freckles.
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Put your hands together
Which thumb is on top—your left or your right?
One study found that 55% of people place their left thumb on top, 45% place their right thumb on top, and 1% have no preference.
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Red-green colorblindness is caused by a single gene located on the X-chromosome.
red-green colorblindness is much more frequent in boys (1 in 12) than in girls (1 in 250).
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If your hairline forms a point at the center of the forehead, you have a widow's peak. If not, you have a straight hairline
