The traits and features found on any organism are typically the effects of genetic inheritance--aspects of appearance and functionality that are passed down from a parent plant or animal to its offspring. Known as inherited traits, the features that children can receive from their parents range widely and are not always obvious. From the colour of your skin to the shape of your blood cells, you are a combination of mother and father inside and out.
Your appearance is effected by genetic inheritance in every way. The shape of facial features like the eyes, ears, nose, mouth and chin are all determined by the alleles (genetics traits) you receive from your parents. When a distant aunt or cousin exclaims "she has her father's eyes and her mother's nose," the meaning can be quite literal. However, inherited physical traits can mean more than eye colour and mouth size: body shape, height, weight, hairline and even voice are determined by the traits passed down through earlier generations, and as the body ages, some traits--like baldness or body shape--change in exactly the same way as the parents traits did.
The disposition a child maintains can be inherited from parents and grandparents. Though many personality traits are learnt from parent interactions and life experiences, some aspects of a child's personality can be attributed to genetics. In 2008, scientists at the University of Edinburgh in Australia determined that some markers in the human genetic code actually cause a particular individual to be generally happier than others. Though outside situations and environments can change the base level of happiness for a person, some with inherited happiness can react to adverse situations in a more positive way. Other aspects of personality can also be underlined by a genetic inheritance, particularly in situations where a trait is common between parent and child.
Some inherited traits result in quirky or uncommon characteristics. For instance, the ability to roll the tongue (curl both sides of the tongue upward until they meet) is an inherited trait that simply functions as a source of amusement for individuals who can roll their tongues. Hitchhiker's thumb, a trait that causes the upper joint of the thumb to curl backward rather than stand straight, is another seemingly useless inherited trait. Elongated second toes, attached and detached ear lobes, and even the ability to make the Vulcan hand wave from "Star Trek" are genetic quirks that can pass from parent to child or skip generations to grandchildren.
Unfortunately, the ability to pass on genetic traits does not mean that only good genes make the list. Many disorders or dysfunctions of the human body can be passed on to offspring through the genetic code. In fact, an entire series of disorders, known as congenital or genetic disorders, can occur as a cause of malfunctioning DNA. Cleft lips and palates, heart defects, cystic fibrosis, down syndrome and Trisomy 18 are all very serious genetic disorders that can appear in a child's inherited traits. Many of these disorders are not manifest in parents or skip many generations before surfacing, making some of them hard to trace or predict.